UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON,Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to SectionPROXY STATEMENT PURSUANT TO SECTION 14(a) of the SecuritiesOF THE

Exchange Act ofSECURITIES EXCHANGE ACT OF 1934 (Amendment No.           )

Filed by the Registrant  ☒

Filed by a Party other than the Registrant  ☐

Check the appropriate box:

☐      Preliminary Proxy Statement

☐      Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

☒      Definitive Proxy Statement

☐      Definitive Additional Materials

☐      Soliciting Material Pursuant to §240.14a-11(c) or §240.14a-12

COLUMBIA FUNDS SERIES TRUSTColumbia Funds Series Trust I

(Name of Registrant as Specified In Itsin its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

IMPORTANT NOTICE REGARDING CHANGE IN INVESTMENT POLICY

COLUMBIA FUNDS SERIES TRUST I

COLUMBIA SMALL CAP GROWTH FUND I

April 10, 2020

The Board of Trustees of Columbia Funds Series Trust I on behalf of the Columbia Small Cap Growth Fund I (the “Fund”), has approved the following changes to the investment policies of the Fund:

These investment policy changes, as described further in the accompanying Proxy Statement, are contingent upon shareholders approving the conversion of the Fund’s investment objective from a “fundamental” investment objective to a “non-fundamental” investment objective (the “Proposal”). If the Proposal is approved, these investment policy changes will take effect as soon as practicable upon completion of the June 30, 2020 special meeting of shareholders, including any adjournments or postponements thereof. Shareholders are strongly encouraged to read the accompanying Proxy Statement and submit their proxies or voting instructions as soon as possible.

PLEASE KEEP THIS NOTICE FOR FUTURE REFERENCE

COLUMBIA FUNDS SERIES TRUST I

COLUMBIA SMALL CAP GROWTH FUND I

225 Franklin290 Congress Street, Boston, Massachusetts 0211002210

JOINT SPECIAL MEETING OF SHAREHOLDERS

To be held on May 15, 2023

Columbia Adaptive Retirement 2020 Fund

Columbia Adaptive Retirement 2025 Fund

Columbia Adaptive Retirement 2030 Fund

Columbia Adaptive Retirement 2035 Fund

Columbia Adaptive Retirement 2040 Fund

Columbia Adaptive Retirement 2045 Fund

Columbia Adaptive Retirement 2050 Fund

Columbia Adaptive Retirement 2055 Fund

Columbia Adaptive Retirement 2060 Fund

IMPORTANT INFORMATION TO HELP YOU UNDERSTAND AND VOTE ON THE PROPOSAL

Important Information to Help You UnderstandThe following Questions and Vote on the Proposal

This isAnswers provide a brief overview of the matter on which you are being asked to vote. The accompanying Proxy Statement contains more detailed information about the proposal, and we encourage you to read it in its entirety before voting. Your vote is important.voting.

YOUR VOTE IS IMPORTANT.

The Proposal would “bundle” the current fee structure of the Funds into a “unified fee” whereby the Investment Manager would pay all of the operating costs and expenses of each Fund other than taxes, interest, brokerage expenses, portfolio transaction expenses, fees pursuant to a 12b-1 plan, if any, and infrequent and/or unusual expenses, including but not limited to, litigation expenses. The “bundled fee” for Class Adv and Class Inst3 would be 0.55% and 0.30% of the average daily net assets of each class, respectively. The bundled fee structure would result in the reduction of the net annual Fund operating expenses payable by the current shareholders of each class of shares of the Funds. Additionally, in connection with the approval of the proposal, the Investment Manager has agreed to implement a contractual expense limitation that will cap the total Fund operating expenses borne by the Fund’s existing shareholders for so long as the Investment Manager manages the Fund (exclusive of the same fees and expenses that are excluded from the current expense cap but including any acquired fund fees and expenses that would otherwise be borne indirectly by Fund shareholders), unless the contractual expense limitation is sooner terminated in the sole discretion of the Board of Trustees of the Trust (the “Board”), at an annual rate of 0.55% and 0.30% of a Fund’s average daily net assets for Class Adv and Class Inst3, respectively. Under the proposed expense cap, the Investment Manager would bear any acquired fund fees and expenses. None of the Funds’ operations or how the Investment Manager manages any of the Funds is expected to change if the Proposal is approved by Fund shareholders. Other than the bundling of the fee arrangements and certain corresponding changes, the Management Agreement would remain the same in all respects.

Comparisons of the fee rates for the Funds, and, gross and net expense ratios, are included in the accompanying Proxy Statement.

-ii-

-iii-

ii-iv-

NOTICE OF A JOINT SPECIAL MEETING OF SHAREHOLDERS

COLUMBIA FUNDS SERIES TRUST IColumbia Adaptive Retirement 2020 Fund

COLUMBIA SMALL CAP GROWTH FUND IColumbia Adaptive Retirement 2025 Fund

Columbia Adaptive Retirement 2030 Fund

Columbia Adaptive Retirement 2035 Fund

Columbia Adaptive Retirement 2040 Fund

Columbia Adaptive Retirement 2045 Fund

Columbia Adaptive Retirement 2050 Fund

Columbia Adaptive Retirement 2055 Fund

Columbia Adaptive Retirement 2060 Fund

(each a “Fund” and, collectively, the “Funds”)

To be held on June 30, 2020May 15, 2023

A Joint Special Meeting of Shareholders (the “Meeting”) of Columbia Small Cap Growth Fund I (the “Fund”) will be held at 225 Franklin Street, Boston, Massachusetts 02110 (32^nd Floor, Room 3200), at 10:00 a.m. (Eastern) on June 30, 2020. The Boardeach of Trustees (the “Board”)the Funds, each a series of Columbia Funds Series Trust I is soliciting proxies for the Meeting.(the “Trust”), will be held at 290 Congress Street (6^th Floor), Boston, Massachusetts, 02210 at 10:00 a.m. local time on May 15, 2023. At the Meeting, shareholders of the Funds at the close of business on March 31, 2023 (the “Record Date”) will be asked:asked to:

Proposal

Please take some time to read the enclosed Proxy Statement. ItStatement, which discusses thethis proposal in more detail. If asyou were a shareholder of a Fund at the close of business on March 20, 2020, you were a shareholder of the Fund,Record Date, you may vote at the Meeting or at any adjournment or postponement of the Meeting. In light ofMeeting on the developing situation withCOVID-19 (coronavirus), shareholders who wishproposal. You are welcome to attend the Meeting are advised to monitor the Fund’s website for updates regarding attendance at the Meeting.in person. If you cannot attend the Meeting in person to cast your vote, please vote by mail, telephone or Internet.internet. Just follow the instructions on the enclosed Proxy Card(s). If you have questions, please call the Fund’sFunds’ proxy solicitor, Computershare Fund Services, toll free at (866)456-7935.866-492-5763. It is important that you vote. The Board of Trustees of the Trust unanimously recommends that you vote FOR the proposal.

By order of the Board of Trustees,

Ryan C. Larrenaga,

Secretary

April 10, 2023

COLUMBIA FUNDS SERIES TRUSTColumbia Funds Series Trust I

COLUMBIA SMALL CAP GROWTH FUND I

225 Franklin290 Congress Street, Boston, Massachusetts 0211002210

Columbia Adaptive Retirement 2020 Fund

Columbia Adaptive Retirement 2025 Fund

Columbia Adaptive Retirement 2030 Fund

Columbia Adaptive Retirement 2035 Fund

Columbia Adaptive Retirement 2040 Fund

Columbia Adaptive Retirement 2045 Fund

Columbia Adaptive Retirement 2050 Fund

Columbia Adaptive Retirement 2055 Fund

Columbia Adaptive Retirement 2060 Fund

(each a “Fund” and, collectively, the “Funds”)

PROXY STATEMENT

Special Meeting of Shareholders JOINT SPECIAL MEETING OF SHAREHOLDERS

to be held on June 30, 2020May 15, 2023

This Proxy Statement is furnished to you in connection with the solicitation of proxies by the Board of Trustees (the “Board” and each member thereof, a “Trustee”) of Columbia Funds Series Trust I (the “Trust”), relating to thea Joint Special Meeting of shareholdersShareholders (the “Meeting”) of each Fund, each a series of the Columbia Small Cap Growth Fund I (the “Fund”), that willTrust, to be held at 225 Franklin290 Congress Street, (6^th Floor), Boston, Massachusetts, 02110 (32^nd Floor, Room 3200),02210 on May 15, 2023 at 10:00 a.m. (Eastern) on June 30, 2020 and any adjournments or postponements thereof.local time. It is expected that this Proxy Statement will be mailed to shareholders on or about April 10, 2020.17, 2023.

The purpose of the Meeting is to ask Fund shareholders as of the close of business on March 31, 2023 (the “Record Date”) to:

Additional information about each Fund is available in its prospectus, statement of additional information and semi-annual and annual reports to shareholders. Each Fund’s most recent semi-annual and annual reports previously have been mailed to shareholders. Additional copies of any of these documents are available without charge upon request by writing Columbia Management Investment Services Corp., P.O. Box 219104, Kansas City, MO 64121-9104 or by calling (800) 345-6611. All of these documents also are filed with the U.S. Securities and Exchange Commission (the “SEC”) and available on the SEC’s website at www.sec.gov.

-1-

TABLE OF CONTENTS

-2-

GENERAL OVERVIEW

Proposal 1: Approve Amendment to Management Agreement

The shareholders of each Fund are being asked to approve a proposed amendment to the Management Agreement between the Trust, on behalf of the Funds, and the Funds’ investment adviser, Columbia Management Investment Advisers, LLC (“Columbia Management” or the “Investment Manager”). The proposed amendment would bundle the Fund’s current fee structure and make certain corresponding changes to the Management Agreement¹. The Proposal would reduce the net annual fund operating expenses payable by the current shareholders of each class of shares of each Fund.

PROPOSAL 1 – APPROVE AMENDMENT TO MANAGEMENT AGREEMENT

Background

The Board has unanimously approved an amendment to the management agreement (the “Management Agreement”) between the Investment Manager and the Trust, on behalf of the Funds. Under the Investment Company Act of 1940 Act, as amended (the “1940 Act”), shareholder approval is required before the Funds can implement the proposed amendment. If shareholders of the Funds do not approve the proposed amendment, the Funds will continue operating pursuant to the Management Agreement currently in effect.

The proposed amendment to the Management Agreement would “bundle” the current fee structure into a “unified fee.” Under the unified fee the Investment Manager would pay all of the operating costs and expenses of each Fund other than, taxes, interest, brokerage expenses, portfolio transaction expenses, fees pursuant to convert the Fund’s investment objective from fundamental toa non-fundamental12b-1 (the “Proposal”). The Board unanimously recommends that shareholders voteFOR theProposal.

Proxy Votingplan, if any, and Shareholder Meeting Information

Proxy Solicitation

Shareholders infrequent and/or the persons named as their proxies may cast votes in their discretion on any other matter that may properly come before the Meeting,unusual expenses, including but not limited to, proposinglitigation expenses. The “bundled fee” for Class Adv and Class Inst 3 would be 0.55% and 0.30% of the average daily net assets of each class, respectively. Under the proposed amendment, the Funds would continue to be managed by Columbia Management and are expected to receive services that are the same as the services provided under the current terms of the management agreement.

The bundled fee structure would result in the reduction of the net annual Fund operating expenses payable by the current shareholders of each class of shares of each Fund. Additionally, in connection with the approval of the proposal, the Investment Manager has agreed to implement a contractual expense limitation that will cap the

-3-

total Fund operating expenses borne by the Fund’s existing shareholders for so long as the Investment Manager manages the Fund (exclusive of the same fees and expenses that are excluded from the current expense cap but including any acquired fund fees and expenses that would otherwise be borne indirectly by Fund shareholders), unless the contractual expense limitation is sooner terminated in the sole discretion of the Board, at an annual rate of 0.55% and 0.30% of a Fund’s average daily net assets for Class Adv and Class Inst3, respectively. Under the proposed expense cap, the Investment Manager would bear any acquired fund fees and expenses.

A description of key terms and provisions of the Management Agreement follows.

Description of Currently Effective Management Agreement and Changes Contemplated by the Proposal

The current management agreement is dated as of October 25, 2016 and was last approved by shareholders of Columbia Adaptive Retirement 2020 Fund, Columbia Adaptive Retirement 2030 Fund, Columbia Adaptive Retirement 2040 Fund, Columbia Adaptive Retirement 2050 Fund and Columbia Adaptive Retirement 2060 Fund on October 23, 2017 and shareholders of Columbia Adaptive Retirement 2025 Fund, Columbia Adaptive Retirement 2035 Fund, Columbia Adaptive Retirement 2045 Fund and Columbia Adaptive Retirement 2055 Fund on April 2, 2018.

The Management Agreement generally provides that, subject to oversight by the Board and the authorized officers of the Trust, Columbia Management agrees to: furnish the Funds continuously with investment advice; determine, consistent with the Funds’ investment objectives, strategies and policies, which investments, in the Investment Manager’s discretion, shall be purchased, held or sold and execute or cause the execution of purchase or sell orders; recommend changes to investment objectives, strategies and policies to the Board, as the Investment Manager deems appropriate; perform investment research and prepare and make available to the Funds research and statistical data in connection therewith and furnish all other services of whatever nature that the Investment Manager from time to time reasonably determines to be necessary or useful in connection with the investment management of the Funds. The Management Agreement adds that Columbia Management will prepare and furnish to the Board such reports, statistical data and other information relating to the investment management of, and the provision of administrative services and facilities to, the Funds in the form and at such intervals as the Board may reasonably request.

Under the Management Agreement, Columbia Management, in selecting brokers or dealers for execution, will seek best execution for securities transactions on behalf of the Funds, except where otherwise directed by the Board. In selecting broker-dealers to execute transactions, Columbia Management may consider not only available prices (including commissions or mark-up), but also other relevant factors such as, without limitation, the characteristics of the security being traded, the size and difficulty of the transaction, the execution, clearance and settlement capabilities as well as the reputation, reliability and financial soundness of the broker-dealer selected, the broker-dealer’s risk

-4-

in positioning a block of securities, the broker-dealer’s execution service rendered on a continuing basis and in other transactions, the broker-dealer’s expertise in particular markets, and the broker-dealers ability to provide research services. The Management Agreement explicitly contemplates that Columbia Management may, except where otherwise directed by the Board, execute transactions or pay to a broker or dealer a commission or markup in excess of that which another broker-dealer might have charged for executing a transaction, provided that the Investment Manager determines, in good faith, that the execution is appropriate or the commission or markup is reasonable in relation to the value of the brokerage and/or voting on the adjournmentresearch services provided, viewed in terms of the Meetingeither that particular transaction or Columbia Management’s overall responsibilities with respect to the Proposal,Funds and other clients for which it acts as investment adviser. Columbia Management will not consider the sale or promotion of shares of the Funds, or other affiliated products, as a factor in the eventsection of broker-dealers through which transactions are executed.

The Management Agreement contemplates the engagement by Columbia Management of subadvisers for the Funds, and provides that sufficient votes in favorColumbia Management may subcontract and pay for certain of the Proposalservices (including with affiliates of Columbia Management) described under the Management Agreement, with the understanding that the quality and level of services required to be provided under the agreement will not be diminished thereby and with the further understanding that Columbia Management will obtain the approval of the Board and/or the Funds’ shareholders as required by applicable law, rules, regulations promulgated thereunder, the terms of the Management Agreement, resolutions of the Board and Columbia Management’s commitments. Currently, the Funds’ assets are not received.managed by any investment subadviser, but instead managed directly by Columbia Management.

The Management Agreement contemplates that Columbia Management will provide support as required or requested by the Board with respect to voting proxies solicited by or with respect to the issuers of securities owned by the Funds. The Management Agreement also contemplates that Columbia Management may vote proxies and provide or withhold consents as directed by the Board from time to time.

The Management Agreement generally requires that all information provided by the Funds to Columbia Management and vice versa be treated as confidential and non-disclosable to unaffiliated third parties except under limited circumstances. The Management Agreement generally requires books and records to be maintained by Columbia Management on behalf of the Funds. The Proposal would not change any of the above.

Fees Under the Current Agreement and Under the Proposal

Under the Management Agreement, the Funds pay a fee that is based on a percentage of the average daily net assets of each Fund. The Management Agreement provides for such fees to be accrued daily and paid monthly.

-5-

Currently, each Fund offers two share classes, Class Advisor (“Class Adv”) and Class Institutional 3 (“Class Inst3”). Shareholders of each Class pay the Investment Manager a fee for its investment management services (currently an effective annual rate of 0.46% of the average daily net assets of each Fund). In return for this fee, the Investment Manager manages the day-to-day operations of the Funds, determines what securities and other investments each Fund should buy or sell and executes portfolio transactions for each Fund. The Investment Manager is also responsible for overseeing the administrative operations of the Fund, including the general supervision of the Fund’s operations, the coordination of the Fund’s other service providers and the provision of related clerical and administrative services, but the Funds are responsible for the expenses of such services.

The Proposal would “bundle” the current fee structure of the Funds into a “unified fee” paid to the Investment Manager to cover operating expenses of the Fund in addition to the investment management and administrative services covered by the current management agreement. The unified fee would cover all of the operating costs and expenses of each Fund other than taxes, interest, brokerage expenses, portfolio transaction expenses, fees pursuant to a 12b-1 plan, if any, and infrequent and/or unusual expenses, including but not limited to, litigation expenses (together, the “Exclusions”).

Under the Proposal, Class Adv and Class Inst3 will pay a single unified fee at an annual rate of 0.55% and 0.30% of the average daily net assets of Class Adv and Class Inst3 shares, respectively. The proposed 0.55% unified fee rate for Class Adv is made up of two components: a core advisory fee rate of 0.30%, plus a 0.25% class-specific administration fee component which covers class-specific shareholder service-related expenses, including payment to intermediaries of up to 0.25% for sub-transfer agency services provided to Class Adv shareholders. The proposed 0.30% unified fee rate for Class Inst3 also includes the 0.30% core advisory fee component, but is not subject to a class-specific shareholder-service component. Under the existing agreement, both classes pay a management fee, currently at an effective annual rate of 0.46% of the average daily net assets of each Fund (see footnote 1 to the table below), but that management fee, unlike the unified fee under the Proposal, does not cover any other operating expenses of the Fund to which shareholders of either class are subject. Under the Proposal, the Investment Manager, and not the Fund, will be responsible for all operating expenses of the Fund for both classes of shares other than the Exclusions. Set forth below is a comparison of current management fees for each class of shares of the Fund under the current terms of the Management Agreement versus total fees and expenses under the unified fee approach under the proposed amended Management Agreement.

-6-

Current and Proposed Fee Rates

Comparison of Management Fee Rates

The management fee rates shown in the above table do not account for any contractual expense limitation agreements between Columbia Management and the Funds. Columbia Management has agreed to implement a contractual expense limitation that will cap the total Fund operating expenses borne by each Fund’s shareholders for so long as Columbia Management manages the Fund (exclusive of the

-7-

same fees and expenses that are excluded from the current expense cap, but including any acquired fund fees and expenses that would otherwise be borne indirectly by Fund shareholders), unless the contractual expense limitation is sooner terminated in the sole discretion of the Board, at an annual rate of 0.55% and 0.30% of each Fund’s average daily net assets for Class Adv and Class Inst3 shares, respectively. See Appendix A for tables showing each Fund’s expenses (by class) for the semiannual period ended September 30, 2022, annualized, as compared to the expenses each Fund would have incurred during that period had the Proposal been approved by shareholders and implemented at the beginning of that period. Please note that pro forma expense information in Appendix A is based on estimates; the actual expenses of the Funds may be different. As shown in Appendix A, the Proposal is expected to reduce the total expenses borne by shareholders of each class of each Fund.

Liability

Under the Management Agreement, and subject to U.S. federal securities laws, except for willful misfeasance, bad faith or negligence on the part of Columbia Management in the performance of its duties, or reckless disregard by Columbia Management of its obligations and duties, neither Columbia Management nor any of its directors, officers, partners, principals, employees, subcontractors or agents will be liable for any acts or omissions or for any loss suffered by the Funds or the Funds’ shareholders or creditors. The Proposal would not change the Management Agreement’s liability provisions.

Effectiveness of the Proposal

If approved, it is expected that the changes would be implemented in early June 2023.

If shareholders of a Fund fail to approve the proposed amendment on behalf of a Fund, then Columbia Management will continue to serve as investment manager to such Fund pursuant to the terms of the current management agreement. All terms and conditions of the current management agreement that are currently in effect, including the fee structure, would remain in effect with respect to such Fund. If shareholders of Class Adv of a Fund fail to approve the Proposal, then the Proposal will not be implemented.

Board Deliberations

On March 10, 2023, the Board and the Funds’ Trustees who are not “interested persons” of the Funds, as defined in the Investment Company Act of 1940 (the “1940 Act”) (the “Independent Trustees”), unanimously approved the amendment to the Management Agreement with Columbia Management with respect to each of the Funds. As detailed below, the Board’s Contracts Committee (the “Committee”) and the Board held meetings to review and discuss, among themselves and with the management team of Columbia Management, materials provided by Columbia Management before determining to approve the proposed changes to the fee structure payable by the Funds.

-8-

In connection with their deliberations regarding the proposed amendment to the Management Agreement, the Committee and the Board evaluated materials requested from Columbia Management regarding the Funds and the Management Agreement with representatives of Columbia Management at a Committee meeting held on March 9, 2023. The Board and its various committees considered matters bearing on the Management Agreement at other meetings throughout the year and meets regularly with senior management of the Trust and Columbia Management. Through the Board’s Investment Review Committee, Trustees also meet with selected portfolio managers of the Funds and with other investment personnel at various times throughout the year. In addition, the Trustees considered the information that they had obtained in connection with the June 2022 continuance of the existing Management Agreement. On March 9, 2023, the Contracts Committee recommended that the Board approve the amendment to the Management Agreement. On March 10, 2023, the Board, including the Independent Trustees, voting separately, unanimously approved the proposed amendment to the Management Agreement for each of the Funds.

The Trustees considered that the Proposal would bundle each Fund’s fees into a unified fee structure. The Board also considered Columbia Management’s contractual agreement to cap the total Fund operating expenses borne by each Fund’s shareholders for so long as the Investment Manager manages the Fund (exclusive of the same fees and expenses that are excluded from the current expense cap but including any acquired fund fees and expenses that would otherwise be borne indirectly by Fund shareholders), unless the contractual expense limitation is sooner terminated in the sole discretion of the Board, to 0.55% and 0.30% of the Funds’ average daily net assets for the two share classes that each Fund offers, Class Advisor (“Class Adv”) and Class Institutional 3 (“Class Inst3”) shares, respectively.

The Committee and the Board considered all information that they, their legal counsel, and the Investment Manager believed reasonably necessary to evaluate and to determine whether to recommend for approval or approve the proposed amendment to the Management Agreement. Among other things, the information and factors considered included the following:

-9-

Following an analysis and discussion of the foregoing, and the factors identified below, the Board, including all of the Independent Trustees, approved the proposed amendment to the Management Agreement.

Nature, Extent and Quality of Services Provided under the Management Agreement

The Board took into account various reports and presentations it had received detailing the services performed by the Investment Manager, as well as its history, expertise, resources and relative capabilities, and the qualifications of its personnel.

In connection with the Board’s evaluation of the overall package of services provided by the Investment Manager, the Board also considered the nature, quality and range of administrative services provided to the Funds by the Investment Manager. In evaluating the quality of services provided under the Management Agreement, the Board also took into account the organization and strength of the Funds’ and their service providers’ compliance programs. The Board also reviewed the financial condition of the Investment Manager and its affiliates and each entity’s ability to carry out its responsibilities under the Management Agreement and the Funds’ other service agreements.

In addition, the Board discussed the acceptability of the terms of the Management Agreement as proposed to be amended, noting that, other than with respect to the fees, no material changes were proposed from the form of agreement previously approved. It was also noted that there were no proposed changes in services to be provided to the Funds. In this regard, the Board also noted the wide array of legal and compliance services provided to the Funds under the Management Agreement.

-10-

After reviewing these and related factors (including investment performance as discussed below), the Board concluded, within the context of their overall conclusions, that the nature, extent and quality of the services provided to the Funds under the Management Agreement supported approval of the proposed amendment to the Management Agreement.

Investment Performance

In this connection, the Board reviewed the investment performance of the Funds. With respect to each of the Funds, the Board observed that performance was well within the range of that of its peers for certain periods.

The Board also considered the Investment Manager’s performance and reputation generally. After reviewing these and related factors, the Board concluded, within the context of their overall conclusions, that the performance of the Funds and the Investment Manager, in light of other considerations, supported approval of the proposed amendment to the Management Agreement.

Comparative fees, costs of services provided and the profits realized by the Investment Manager and its affiliates from their relationships with the Funds

The Board reviewed comparative fees and the costs of services provided under the Management Agreement. The Board members considered information showing a comparison of the Funds’ expenses with median expenses paid by funds in their comparative peer universes, as well as data showing the Funds’ contribution to the Investment Manager’s profitability. The Trustees also reviewed, in detail, the various components of fees/expenses covered under the proposed unified fee structure, including the shareholder service component of the fee for the affected classes. The Trustees considered, in particular, that implementation of the amendment to the Management Agreement would result in lower total expenses for each class of shares of each Fund.

The Board also took into account that each Fund’s total expense ratio (after considering the proposed amendment and the related expense caps/waivers) was below the peer universe’s median expense ratio.

After reviewing these and related factors, the Board concluded, within the context of their overall conclusions, that the levels of management fees and expenses of the Funds, in light of other considerations, supported approval of the proposed amendment to the Management Agreement.

The Board also considered the profitability of the Investment Manager and its affiliates in connection with the Investment Manager providing management services to the Funds. With respect to the profitability of the Investment Manager and its affiliates, the Independent Trustees referred to information discussing the profitability to the Investment Manager and Ameriprise Financial from managing, operating and distributing the Columbia Funds. It also took into account the indirect economic benefits flowing to the Investment Manager or its affiliates in connection with

-11-

managing or distributing the Columbia Funds, such as the enhanced ability to offer various other financial products to Ameriprise Financial customers, soft dollar benefits and overall reputational advantages. The Board noted that the fees paid by the Funds should permit the Investment Manager to offer competitive compensation to its personnel, make necessary investments in its business and earn an appropriate profit. It was considered that implementation of the proposed amendment was projected to slightly reduce the profitability to the Investment Manager from the Funds. After reviewing these and related factors, the Board concluded, within the context of their overall conclusions, that the costs of services provided and the profitability to the Investment Manager and its affiliates from their relationships with the Funds supported approval of the proposed amendment to the Management Agreement.

Economies of Scale

The Board considered the economies of scale that might be realized as the Funds’ net asset level grows. The Board took into account, however, that the proposed amendments to the Management Agreement would obligate Columbia Threadneedle to provide, or pay for the provision of, a greater range of services to the Funds irrespective of the asset level of each Fund. The Board observed that the proposed amendment to the Management Agreement provides for a relatively low flat fee.

Conclusion

The Board reviewed all of the above considerations in reaching its decision to approve the proposed amendment to the Management Agreement for each Fund. In reaching its conclusions, no single factor was determinative.

On March 10, 2023, the Board, including all of the Independent Trustees, determined, with respect to each Fund, that the proposed fees payable under the Management Agreement were fair and reasonable in light of the extent and quality of services provided and approved the proposed amendment to the Management Agreement and recommends that shareholders of each of the Funds vote “FOR” the approval of the proposed amendment.

Required Vote and Recommendation

For each Fund, approval of the amendment to the Management Agreement requires the affirmative vote of a “majority of the outstanding voting securities” of the Fund, which for this purpose means the affirmative vote of the lesser of (i) more than 50% of the outstanding voting securities of the Fund or (ii) 67% or more of the outstanding voting securities of such Fund present at the Meeting if more than 50% of the outstanding voting securities of the Fund are present at the Meeting in person or represented by proxy. All classes of shares of each Fund will vote together on Proposal 1 as it relates to each Fund. In addition, Class Adv shareholders of each Fund will be voting separately on the Proposal for their Fund.

THE BOARD UNANIMOUSLY RECOMMENDS THAT SHAREHOLDERS VOTE FOR THE APPROVAL OF THE PROPOSED AMENDMENT TO THE MANAGEMENT AGREEMENT.

-12-

PROXY VOTING AND SHAREHOLDER MEETING INFORMATION

Proxy Solicitation

If you properly authorize your proxy through the Internetinternet or telephonically, or by executing and returning the enclosed Proxy Card, and your proxy is not subsequently revoked, your votes will be cast at the Meeting. If you give instructions, your votes will be cast in accordance with your instructions. If you return your signed Proxy Card without instructions, your votes will be cast FOR the Proposal.approval of the proposed amendment to the Management Agreement between the Trust, on behalf of the Fund you hold shares of, and Columbia Management, which provides for bundling the current fee structure payable by the Funds (Proposal 1). Your votes will be cast in the discretion of the proxy holders on any other matter that may properly come before the Meeting, including, but not limited to, proposing and/or voting on the adjournment and/or postponement of the Meeting with respect to the Proposal in the event thatproposal if a quorum is not obtained and/or sufficient votes in favor of the Proposalproposal are not received.

Revocation of Proxies and Voting Instructions

If you execute and submit a proxy, you may revoke that proxy or change it by written notice to the Fund’s proxy solicitor at Computershare Fund Services

-1-

c/o Operations Department, 2950 Express Drive South, Suite 210, Islandia, New York 11749, by submitting a subsequently executed and dated Proxy Card, by authorizing your proxy by telephone or Internet,internet, or by attending the Meeting and casting your vote in person, or as otherwise permitted. Attending the Meeting in person will not automatically revoke your prior proxy. If you intend to vote in person at the Meeting, please call Computershare Fund Services, toll free at (866)456-7935.866-492-5763 to obtain important information regarding your attendance at the Meeting, including directions.

Quorum and Methods of Tabulation

A quorum is required to take action on the Proposal. Thirty percent (30%) of the votesshares of a Fund entitled to be cast at the Meeting,vote, present at the Meeting in person or by proxy, constitutes a quorum. Abstentions, withheld authority and “brokernon-votes” (i.e., shares heldquorum of record by a financial intermediary, such as a broker, or nominee, typically in “street name,” as to which proxies have been returned but (i) instructions have not been received from the beneficial owners or persons entitled to vote and (ii) the broker or nominee does not have discretionary voting power on a particular matter) will be treated as present for purposes of determining a quorum but will not be considered a vote cast.each Fund.

In the event that a quorum of shareholders of thea Fund is not present at the Meeting or, even if such a quorum is so present, in the event that sufficient votes in favor of the Proposalproposal are not received and tabulated prior to the time the Meeting is called to order, the Meeting may be adjourned by the vote of a majority of the shares represented at the Meeting, either in person or by proxy, and further solicitations may be made.

Shareholders of record of theeach Fund at the close of business on March 20, 202031, 2023 (the “Record Date”)Record Date) are entitled to notice of, and to vote at, the Meeting. The number of outstanding shares of each class of shares of theeach Fund held on the Record Date is listedshown inAppendixA. the table below. Shareholders of the FundFunds are entitled to one vote for each dollar of net asset value (number of shares owned times net asset value per share) determined at the close of business on the Record Date and each fractional dollar amount is entitled to a proportionate fractional vote.

-13-

If your shares are held in an IRA account, you have the right to vote those shares. If you do not provide voting instructions with respect to your shares, your IRA custodian may or may not, depending upon the terms of your IRA agreement, vote shares for which it has not received your voting instructions. Please consult your IRA agreement and/or financial advisor for more information.

Effect of Abstentions and Broker Required VoteNon-Votes

For all matters to be voted upon, an abstention or broker Conversionnon-vote will not be considered a vote cast; however, an abstention will be counted for purposes of attaining a quorum. Abstentions will have the Fund’s investment objective from fundamentalsame effect as a vote against the proposal. Because the only proposal is non-routine, failure tonon-fundamental requires provide voting instructions to a broker will result in a beneficial owner’s shares not being counted as present at the affirmative voteJoint Special Meeting for purposes of a “majority ofquorum and not being voted on the outstanding voting securities” of the Fund, which for this purpose means the affirmative vote of the lesser of (i) more than 50% of the outstanding voting securities of the Fund or (ii) 67% orproposal.

-2--14-

more of the outstanding voting securities of the Fund that are present at the Meeting if more than 50% of the outstanding voting securities of such Fund are present at the Meeting in person or represented by proxy. All shares of the Fund vote together as a single class on the Proposal.OTHER INFORMATION

Voting InformationCurrent Service Providers

Additional information about the Fund is available in the Fund’s prospectus, statement of additional information and annual and semiannual reports to shareholders. The Fund’s most recent annual and semiannual reports previously have been mailed to shareholders. Additional copies of any of these documents are available without charge upon request by writing to Columbia Funds, c/o Columbia Management, Investment Services Corp., P.O. Box 219104, Kansas City, MO 64121-9104 or by calling(800) 345-6611. All of these documents also are filed with the U.S. Securities and Exchange Commission (the “SEC”) and are available on the SEC’s website at www.sec.gov.

Important Notice Regarding the Availability of Proxy Materials for the Shareholder Meeting to Be Held on June 30, 2020

This Proxy Statement and the Notice of Special Meeting are available atwww.proxy-direct.com/col-31177.

-3-

THE PROPOSAL

The Board has approved, on behalf of the Fund, the conversion of the Fund’s investment objective from a “fundamental” investment objective to a“non-fundamental” investment objective, subject to approval by the Fund’s shareholders. “Fundamental” investment objectives and policies require shareholder approval to change. Changing the investment objective from “fundamental” to“non-fundamental” will give the Board additional flexibility to make any changes to the Fund’s investment objective that it deems appropriate in the future to address changing market conditions or other developments, while saving the Fund’s shareholders the cost and delay of a proxy solicitation. If shareholders approve the Proposal and change the Fund’s investment objective from fundamental tonon-fundamental, the Board will be permitted to make future changes to the Fund’s investment objective without a vote of the Fund’s shareholders.

Shareholders of the Fund are only being asked to approve the conversion of the Fund’s investment objective from fundamental tonon-fundamental. If shareholders approve the Proposal, a new investment objective (the “New Investment Objective”) that has been approved by the Board will take effect as soon as practicable following the Meeting. Columbia Threadneedle recommended that the Board approve the New Investment Objective to provide for increased investment flexibility. The current investment objective and New Investment Objective are shown in the table below:

The Fund has adopted a non-fundamental policy of investing its assets in equity securities of small cap companies defined by reference to the Standard & Poor’s (S&P) Small Cap 600^® Index (the “Current 80% Policy”). If shareholders approve the Proposal, the Board has also approved, on behalf of the Fund, a revised non-fundamental 80% policy (the “New 80% Policy”) to replace the Current 80% Policy. The SEC requires a registered investment company with a term such as “small cap” in its name to adopt a policy generally requiring that 80% of its net assets be invested in investments that are consistent with its name. Pursuant to this requirement, the Fund has adopted the Current 80% Policy. Columbia Threadneedle recommended that the Board adopt the New 80% Policy to align the Fund’s 80% policy with its performance benchmark index, the Russell 2000 Growth Index. The New 80% Policy will allow the Fund to count towards compliance with its policy equity securities of companies with

-4-

both a smaller and larger capitalization than those that count towards compliance with the Current 80% Policy. Securities of smaller capitalization companies may be subject to greater price volatility and may decline more significantly in market downturns than securities of larger companies. The Current 80% Policy and New 80% Policy are shown in the table below:

Required Vote and Recommendation

Conversion of the Fund’s investment objective from fundamental tonon-fundamental requires the affirmative vote of a “majority of the outstanding voting securities” of the Fund, which for this purpose means the affirmative vote of the lesser of (i) more than 50% of the outstanding voting securities of the Fund or (ii) 67% or more of the outstanding voting securities of the Fund that are present at the Meeting if more than 50% of the outstanding voting securities of such Fund are present at the Meeting in person or represented by proxy.

THE BOARD UNANIMOUSLY RECOMMENDS THAT SHAREHOLDERS VOTE FOR THE PROPOSAL.

-5-

OTHER INFORMATION

Columbia Threadneedle, located at 225 Franklin290 Congress Street, Boston, Massachusetts 02110,02210, serves as the investment manager ofand administrator to the Fund and the other Columbia Funds. Columbia Management Investment Distributors, Inc. (the “Distributor”), also located at 225 Franklin290 Congress Street, Boston, Massachusetts 02110,02210, serves as the principal underwriter of the Fund. Columbia Threadneedle and Columbia Management Investment Distributors, Inc. are subsidiaries of Ameriprise Financial, Inc.Funds. The Funds paid no commissions to any affiliated brokers during the Funds’ most recent fiscal year.

Other Matters to Come Before the Meeting

Columbia ThreadneedleManagement does not know of any matters to be presented at the Meeting other than thosethe Proposal described in this Proxy Statement. If other business should properly come before the Meeting, the persons named as proxies will vote thereon in accordance with their best judgment.

Procedures for Communications to the Board

Shareholders who want to communicate with the Board or an individual Trustee must send written communications to the Trust, c/o the Secretary, 225 Franklin Street, Boston, Massachusetts 02110, addressed to the Board of Trustees of the Fund or the individual Trustee. The Secretary may determine not to forward to the Board any letter that does not relate to the business of the Fund.

Proposals of Shareholders

The Trust does not generallyregularly hold annual shareholders’shareholder meetings, but will holdmay from time to time schedule special meetings as required or deemed desirable bymeetings. In accordance with the Board. Because the Trust does not hold regular shareholders’ meetings, the anticipated dateregulations of the next shareholders’ meeting (if any) cannotSEC, in order to be provided. Shareholders wishing to submit proposalseligible for inclusion in athe Trust’s proxy statement for such a subsequent shareholders’ meeting, of the Trust, including submitting nominees for election as Trustees, should send their written proposals to the Trust, c/o the Secretary, 225 Franklin Street, Boston, Massachusetts 02110. Proposalsa shareholder proposal must be received in a reasonable time before the Trust begins to printprints and mail themails its proxy materials for a shareholders’ meeting. The timely submission of a proposal does not guarantee its inclusion.statement.

Principal Shareholders

AppendixA B to this Proxy Statement lists the persons that, to the knowledge of theeach Fund, owned beneficially 5% or more of the outstanding shares of any class of the FundFunds as of the Record Date.March 31, 2023. A shareholder who owns beneficially, directly or indirectly, more than 25% of theany Fund’s voting securities is presumed to be a “control person” (as defined in the Investment Company Act1940 Act) of 1940)a Fund. As of March 31, 2023, the Trustees and Officers of the Fund. Columbia Funds managed by Columbia Threadneedle may be presumed under securities laws to control the Fund and may be able to determine the outcome of issues that are submitted to

-6-

shareholders for vote. The Trustees and officers of the Trust,Trusts, in the aggregate, beneficially owned less than 1% of each class of shares of each Fund, except as set forth in the Fund’s outstanding shares as of the Record Date.table below.

Expenses and Solicitation Activities

The Fund will bear allexpenses incurred in connection with the solicitation of proxies for the costsMeeting, including preparation, filing, printing, mailing and solicitation expenses, legal fees, out-of-pocket expenses and expenses of theany proxy solicitation related tofirm, will be paid separately by Columbia Management or an affiliated company and not by the Proposal. These expenses are estimated to be approximately $100,500.

Computershare Fund Services will provide shareholder meeting services and assist in soliciting and tracking votes. The cost for such services is expected to be approximately $80,500 (which is reflected in the overall expenses noted in the preceding paragraph). The agreement with Computershare provides for indemnification of Computershare in certain circumstances, includes typical representations and warranties, sets forth service level standards and requires Computershare to keep certain information confidential.Funds. In addition to the use of the mail,mails, proxies may be solicited personally or via facsimile, telephone or the Internet by trustees,Trustees, officers and employees of the Trust, Columbia Threadneedle,

-15-

Management, Columbia Management Investment Distributors, Inc. and the Fund’s transfer agent, Columbia Management Investment Services Corp. The Funds have engaged Computershare Fund Services to assist in soliciting at an estimated cost of approximately $12,319, which will be paid by Columbia Management or an affiliated company.

Fiscal Year

The last fiscal year end for the Fund was August 31, 2019.

Proxy Statement Delivery

“Householding” is the term used to describe the practice of delivering one copy of a document to a household of shareholders instead of delivering one copy of a document to each shareholder in the household. Shareholders of thea Fund who share a common address and who have not opted out of the householding process should receive a single copy of the Proxy Statement together with one Proxy Card for each account. If you received more than one copy of the Proxy Statement, you may elect to household in the future; if you received a single copy of the Proxy Statement, you may opt out of householding in the future; and you may, in any event, obtain an additional copy of this Proxy Statement by calling (866)456-7935 or writing to the FundFunds at the following address: 225 Franklin Street, Boston, Massachusetts 02110, Attention: Secretary. Copies of this Proxy Statement and the accompanying Notice of Special Meeting are also availableComputershare Fund Services, PO Box 5696, Hauppauge, NY 11788-2847, or by calling Computershare Fund Services, toll free atwww.proxy-direct.com/col-31177.866-492-5763.

Shareholder Reports

The Fund’sFunds’ most recent semiannualsemi-annual and annual reportsreport previously have been mailedmade available to shareholders. The FundFunds will furnish, without charge, a copy of itstheir most recent annual shareholder report and their most recent semi-annual shareholder report to their shareholders on request. Additional copies of any of these documents are available by writing to Columbia Funds, c/o Columbia Management Investment Services Corp., P.O. Box 219104, Kansas City, MO 64121-9104 or by calling (800)345-6611. All of these documents also are filed with the SEC and are available on the SEC’s website at www.sec.gov.

-7--16-

PROMPT EXECUTION AND RETURN OF THE ENCLOSED PROXY CARD IS REQUESTED. APRE-ADDRESSED, POSTAGE-PAID ENVELOPE IS ENCLOSED FOR YOUR CONVENIENCE, AND TELEPHONE AND INTERNET VOTING IS AVAILABLE.

By order of the Board of Trustees,

		By order of the Board of Trustees,
		Ryan C. Larrenaga
		Secretary

Ryan C. Larrenaga,

Secretary

It is important that you authorize proxies promptly. All shareholders, including those who expect to attend the Meeting in person, are urged to authorize their proxy as soon as possible by accessing the Internet site listed on the enclosed Proxy Card, by calling the toll-free number listed on the enclosed Proxy Card, or by mailing the enclosed Proxy Card in the enclosed return envelope, which requires no postage if mailed in the United States. To enter the Meeting, you will need proof of ownership of the shares of one or more of the Fund,Funds, such as your Proxy Card (or a copy thereof) or, if your shares are held of record by a financial intermediary, such as a broker, or nominee, a Proxy Card from the record holder or other proof of beneficial ownership, such as a brokerage statement showing your holdings of the shares of thea Fund.

-8--17-

APPENDIX A – Estimated Comparison of Fees and Expenses

Shares OutstandingColumbia Adaptive Retirement 2020 Fund

AsThe information in the table below reflects the fees and expenses for each Fund for the semiannual period ended September 30, 2022 (annualized) and the pro forma projected expenses for each Fund for the semiannual period ended September 30, 2022 (annualized).

Current Fees and Expenses

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

The waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above are reflected in Year 1 and Years 2 through 10 expense examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Pro Forma Fees and Expenses

limited to, litigation expenses. The management fees in the table above represents the unitary fee, which is a combination of Core Investment Advisory Fee and Class-specific Administration Fee. The difference in management fees amongst the share classes is a result of their separate arrangements for non-Rule 12b-1 shareholder services fees (class-specific administration fee). It is not the result of any difference in management or custodial fees, or other expenses related to the management of the Fund’s assets, which do not vary by share class. The Core Investment Advisory Fee is 0.30% across both share classes. The Management fees have been restated to reflect the current management fee rate.

(b)

“Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include acquired fund fees and expenses.

(c)

Columbia Management Investment Advisers, LLC (the Investment Manager) and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, and infrequent and/or unusual expenses) for so long as the Investment Manager manages the Fund, unless sooner terminated at the sole discretion of the Fund’s Board of Trustees. Under this agreement, the Fund’s net operating expenses, subject to applicable exclusions, will not exceed the annual rates of 0.55% for Class Adv and 0.30% for Class Inst3.

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table do not expire as indicated in the preceding table, they are reflected in all of the Record Date,examples.

Although your actual costs may be higher or lower, based on the Fund had outstandingassumptions listed above, your costs would be:

Under the following number of shares of the classes indicated belowcurrent management agreement, Class Adv and each classClass Inst3 of the Fund paid Columbia Management Investment Advisors, LLC (“Columbia Management”) an aggregate management fee of $3,050 and $5,720, respectively, for the fiscal year ended March 31, 2022. If the Proposed Management Agreement had been in effect during the fiscal year ended March 31, 2022, the management fee payable by Class Adv and Class Inst3 to Columbia Management would have been $3,719 and $3,797, respectively. The difference between these amounts is entitled$669 and -$1,923 for Class Adv

and Class Inst3 respectively (or 0.10% and -0.15% of Class Adv and Class Inst3’s aggregate management fee for the fiscal year ended March 31, 2022).

Columbia Adaptive Retirement 2025 Fund

The information in the table below reflects the fees and expenses for each Fund for the semiannual period ended September 30, 2022 (annualized) and the pro forma projected expenses for each Fund for the semiannual period ended September 30, 2022 (annualized).

Current Fees and Expenses

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

The waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above are reflected in Year 1 and Years 2 through 10 expense examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Pro Forma Fees and Expenses

limited to, litigation expenses. The management fees in the table above represents the unitary fee, which is a combination of Core Investment Advisory Fee and Class-specific Administration Fee. The difference in management fees amongst the share classes is a result of their separate arrangements for non-Rule 12b-1 shareholder services fees (class-specific administration fee). It is not the result of any difference in management or custodial fees, or other expenses related to the management of the Fund’s assets, which do not vary by share class. The Core Investment Advisory Fee is 0.30% across both share classes. The Management fees have been restated to reflect the current management fee rate.

(b)

“Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include acquired fund fees and expenses.

(c)

Columbia Management Investment Advisers, LLC (the Investment Manager) and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, and infrequent and/or unusual expenses) for so long as the Investment Manager manages the Fund, unless sooner terminated at the sole discretion of the Fund’s Board of Trustees. Under this agreement, the Fund’s net operating expenses, subject to applicable exclusions, will not exceed the annual rates of 0.55% for Class Adv and 0.30% for Class Inst3.

Example

The following numberexample is intended to help you compare the cost of votesinvesting in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table do not expire as indicated below.in the preceding table, they are reflected in all of the examples.

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Under the current management agreement, Class Adv and Class Inst3 of the Fund paid Columbia Management Investment Advisors, LLC (“Columbia Management”) an aggregate management fee of $3,243 and $3,182, respectively, for the fiscal year ended March 31, 2022. If the Proposed Management Agreement had been in effect during the fiscal year ended March 31, 2022, the management fee payable by Class Adv and Class Inst3 to Columbia Management would have been $3,953 and $2,112, respectively. The difference between these amounts is $710 and -$1,070 for Class Adv

and Class Inst3 respectively (or 0.10% and -0.15% of Class Adv and Class Inst3’s aggregate management fee for the fiscal year ended March 31, 2022).

Columbia Adaptive Retirement 2030 Fund

The information in the table below reflects the fees and expenses for each Fund for the semiannual period ended September 30, 2022 (annualized) and the pro forma projected expenses for each Fund for the semiannual period ended September 30, 2022 (annualized).

Current Fees and Expenses

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

The waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above are reflected in Year 1 and Years 2 through 10 expense examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Pro Forma Fees and Expenses

limited to, litigation expenses. The management fees in the table above represents the unitary fee, which is a combination of Core Investment Advisory Fee and Class-specific Administration Fee. The difference in management fees amongst the share classes is a result of their separate arrangements for non-Rule 12b-1 shareholder services fees (class-specific administration fee). It is not the result of any difference in management or custodial fees, or other expenses related to the management of the Fund’s assets, which do not vary by share class. The Core Investment Advisory Fee is 0.30% across both share classes. The Management fees have been restated to reflect the current management fee rate.

(b)

“Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include acquired fund fees and expenses.

(c)

Columbia Management Investment Advisers, LLC (the Investment Manager) and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, and infrequent and/or unusual expenses) for so long as the Investment Manager manages the Fund, unless sooner terminated at the sole discretion of the Fund’s Board of Trustees. Under this agreement, the Fund’s net operating expenses, subject to applicable exclusions, will not exceed the annual rates of 0.55% for Class Adv and 0.30% for Class Inst3.

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table do not expire as indicated in the preceding table, they are reflected in all of the examples.

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Under the current management agreement, Class Adv and Class Inst3 of the Fund paid Columbia Management Investment Advisors, LLC (“Columbia Management”) an aggregate management fee of $8,610 and $5,117, respectively, for the fiscal year ended March 31, 2022. If the Proposed Management Agreement had been in effect during the fiscal year ended March 31, 2022, the management fee payable by Class Adv and Class Inst3 to Columbia Management would have been $10,492 and $3,395, respectively. The difference between these amounts is $1,882 and -$1,722 for

Class Adv and Class Inst3 respectively (or 0.10% and -0.15% of Class Adv and Class Inst3’s aggregate management fee for the fiscal year ended March 31, 2022).

Columbia Adaptive Retirement 2035 Fund

The information in the table below reflects the fees and expenses for each Fund for the semiannual period ended September 30, 2022 (annualized) and the pro forma projected expenses for each Fund for the semiannual period ended September 30, 2022 (annualized).

Current Fees and Expenses

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

The waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above are reflected in Year 1 and Years 2 through 10 expense examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Pro Forma Fees and Expenses

limited to, litigation expenses. The management fees in the table above represents the unitary fee, which is a combination of Core Investment Advisory Fee and Class-specific Administration Fee. The difference in management fees amongst the share classes is a result of their separate arrangements for non-Rule 12b-1 shareholder services fees (class-specific administration fee). It is not the result of any difference in management or custodial fees, or other expenses related to the management of the Fund’s assets, which do not vary by share class. The Core Investment Advisory Fee is 0.30% across both share classes. The Management fees have been restated to reflect the current management fee rate.

(b)

“Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include acquired fund fees and expenses.

(c)

Columbia Management Investment Advisers, LLC (the Investment Manager) and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, and infrequent and/or unusual expenses) for so long as the Investment Manager manages the Fund, unless sooner terminated at the sole discretion of the Fund’s Board of Trustees. Under this agreement, the Fund’s net operating expenses, subject to applicable exclusions, will not exceed the annual rates of 0.55% for Class Adv and 0.30% for Class Inst3.

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table do not expire as indicated in the preceding table, they are reflected in all of the examples.

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Under the current management agreement, Class Adv and Class Inst3 of the Fund paid Columbia Management Investment Advisors, LLC (“Columbia Management”) an aggregate management fee of $4,666 and $4,043, respectively, for the fiscal year ended March 31, 2022. If the Proposed Management Agreement had been in effect during the fiscal year ended March 31, 2022, the management fee payable by Class Adv and Class Inst3 to Columbia Management would have been $5,687 and $2,683, respectively. The difference between these amounts is $1,021 and -$1,360 for

Class Adv and Class Inst3 respectively (or 0.10% and -0.15% of Class Adv and Class Inst3’s aggregate management fee for the fiscal year ended March 31, 2022).

Columbia Adaptive Retirement 2040 Fund

The information in the table below reflects the fees and expenses for each Fund for the semiannual period ended September 30, 2022 (annualized) and the pro forma projected expenses for each Fund for the semiannual period ended September 30, 2022 (annualized).

Current Fees and Expenses

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

The waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above are reflected in Year 1 and Years 2 through 10 expense examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Pro Forma Fees and Expenses

limited to, litigation expenses. The management fees in the table above represents the unitary fee, which is a combination of Core Investment Advisory Fee and Class-specific Administration Fee. The difference in management fees amongst the share classes is a result of their separate arrangements for non-Rule 12b-1 shareholder services fees (class-specific administration fee). It is not the result of any difference in management or custodial fees, or other expenses related to the management of the Fund’s assets, which do not vary by share class. The Core Investment Advisory Fee is 0.30% across both share classes. The Management fees have been restated to reflect the current management fee rate.

(b)

“Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include acquired fund fees and expenses.

(c)

Columbia Management Investment Advisers, LLC (the Investment Manager) and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, and infrequent and/or unusual expenses) for so long as the Investment Manager manages the Fund, unless sooner terminated at the sole discretion of the Fund’s Board of Trustees. Under this agreement, the Fund’s net operating expenses, subject to applicable exclusions, will not exceed the annual rates of 0.55% for Class Adv and 0.30% for Class Inst3.

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table do not expire as indicated in the preceding table, they are reflected in all of the examples.

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Under the current management agreement, Class Adv and Class Inst3 of the Fund paid Columbia Management Investment Advisors, LLC (“Columbia Management”) an aggregate management fee of $3,715 and $5,109, respectively, for the fiscal year ended March 31, 2022. If the Proposed Management Agreement had been in effect during the fiscal year ended March 31, 2022, the management fee payable by Class Adv and Class Inst3 to Columbia Management would have been $4,527 and $3,391, respectively. The difference between these amounts is $812 and -$1,718 for Class Adv

and Class Inst3 respectively (or 0.10% and -0.15% of Class Adv and Class Inst3’s aggregate management fee for the fiscal year ended March 31, 2022).

Columbia Adaptive Retirement 2045 Fund

The information in the table below reflects the fees and expenses for each Fund for the semiannual period ended September 30, 2022 (annualized) and the pro forma projected expenses for each Fund for the semiannual period ended September 30, 2022 (annualized).

Current Fees and Expenses

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

The waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above are reflected in Year 1 and Years 2 through 10 expense examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Pro Forma Fees and Expenses

limited to, litigation expenses. The management fees in the table above represents the unitary fee, which is a combination of Core Investment Advisory Fee and Class-specific Administration Fee. The difference in management fees amongst the share classes is a result of their separate arrangements for non-Rule 12b-1 shareholder services fees (class-specific administration fee). It is not the result of any difference in management or custodial fees, or other expenses related to the management of the Fund’s assets, which do not vary by share class. The Core Investment Advisory Fee is 0.30% across both share classes. The Management fees have been restated to reflect the current management fee rate.

(b)

“Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include acquired fund fees and expenses.

(c)

Columbia Management Investment Advisers, LLC (the Investment Manager) and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, and infrequent and/or unusual expenses) for so long as the Investment Manager manages the Fund, unless sooner terminated at the sole discretion of the Fund’s Board of Trustees. Under this agreement, the Fund’s net operating expenses, subject to applicable exclusions, will not exceed the annual rates of 0.55% for Class Adv and 0.30% for Class Inst3.

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table do not expire as indicated in the preceding table, they are reflected in all of the examples.

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Under the current management agreement, Class Adv and Class Inst3 of the Fund paid Columbia Management Investment Advisors, LLC (“Columbia Management”) an aggregate management fee of $3,103 and $5,030, respectively, for the fiscal year ended March 31, 2022. If the Proposed Management Agreement had been in effect during the fiscal year ended March 31, 2022, the management fee payable by Class Adv and Class Inst3 to Columbia Management would have been $3,781 and $3,339, respectively. The difference between these amounts is $678 and -$1,691 for Class Adv and Class Inst3 respectively (or 0.10% and -0.15% of Class Adv and Class Inst3’s aggregate management fee for the fiscal year ended March 31, 2022).

Columbia Adaptive Retirement 2050 Fund

The information in the table below reflects the fees and expenses for each Fund for the semiannual period ended September 30, 2022 (annualized) and the pro forma projected expenses for each Fund for the semiannual period ended September 30, 2022 (annualized).

Current Fees and Expenses

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

The waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above are reflected in Year 1 and Years 2 through 10 expense examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Pro Forma Fees and Expenses

limited to, litigation expenses. The management fees in the table above represents the unitary fee, which is a combination of Core Investment Advisory Fee and Class-specific Administration Fee. The difference in management fees amongst the share classes is a result of their separate arrangements for non-Rule 12b-1 shareholder services fees (class-specific administration fee). It is not the result of any difference in management or custodial fees, or other expenses related to the management of the Fund’s assets, which do not vary by share class. The Core Investment Advisory Fee is 0.30% across both share classes. The Management fees have been restated to reflect the current management fee rate.

(b)

“Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include acquired fund fees and expenses.

(c)

Columbia Management Investment Advisers, LLC (the Investment Manager) and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, and infrequent and/or unusual expenses) for so long as the Investment Manager manages the Fund, unless sooner terminated at the sole discretion of the Fund’s Board of Trustees. Under this agreement, the Fund’s net operating expenses, subject to applicable exclusions, will not exceed the annual rates of 0.55% for Class Adv and 0.30% for Class Inst3.

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table do not expire as indicated in the preceding table, they are reflected in all of the examples.

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Under the current management agreement, Class Adv and Class Inst3 of the Fund paid Columbia Management Investment Advisors, LLC (“Columbia Management”) an aggregate management fee of $2,007 and $6,449, respectively, for the fiscal year ended March 31, 2022. If the Proposed Management Agreement had been in effect during the fiscal year ended March 31, 2022, the management fee payable by Class Adv and Class Inst3 to Columbia Management would have been $2,453 and $4,277, respectively. The difference between these amounts is $446 and -$2,172 for Class Adv

and Class Inst3 respectively (or 0.10% and -0.15% of Class Adv and Class Inst3’s aggregate management fee for the fiscal year ended March 31, 2022).

Columbia Adaptive Retirement 2055 Fund

The information in the table below reflects the fees and expenses for each Fund for the semiannual period ended September 30, 2022 (annualized) and the pro forma projected expenses for each Fund for the semiannual period ended September 30, 2022 (annualized).

Current Fees and Expenses

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

The waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above are reflected in Year 1 and Years 2 through 10 expense examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Pro Forma Fees and Expenses

limited to, litigation expenses. The management fees in the table above represents the unitary fee, which is a combination of Core Investment Advisory Fee and Class-specific Administration Fee. The difference in management fees amongst the share classes is a result of their separate arrangements for non-Rule 12b-1 shareholder services fees (class-specific administration fee). It is not the result of any difference in management or custodial fees, or other expenses related to the management of the Fund’s assets, which do not vary by share class. The Core Investment Advisory Fee is 0.30% across both share classes. The Management fees have been restated to reflect the current management fee rate.

(b)

“Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than the ratio of expenses to average net assets shown in the Financial Highlights section of this prospectus because the ratio of expenses to average net assets does not include acquired fund fees and expenses.

(c)

Columbia Management Investment Advisers, LLC (the Investment Manager) and certain of its affiliates have contractually agreed to waive fees and/or to reimburse expenses (excluding transaction costs and certain other investment related expenses, interest, taxes, and infrequent and/or unusual expenses) for so long as the Investment Manager manages the Fund, unless sooner terminated at the sole discretion of the Fund’s Board of Trustees. Under this agreement, the Fund’s net operating expenses, subject to applicable exclusions, will not exceed the annual rates of 0.55% for Class Adv and 0.30% for Class Inst3.

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table do not expire as indicated in the preceding table, they are reflected in all of the examples.

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Under the current management agreement, Class Adv and Class Inst3 of the Fund paid Columbia Management Investment Advisors, LLC (“Columbia Management”) an aggregate management fee of $2,566 and $6,469, respectively, for the fiscal year ended March 31, 2022. If the Proposed Management Agreement had been in effect during the fiscal year ended March 31, 2022, the management fee payable by Class Adv and Class Inst3 to Columbia Management would have been $3,131 and $4,292, respectively. The difference between these amounts is $565 and -$2,177 for Class Adv

and Class Inst3 respectively (or 0.10% and -0.15% of Class Adv and Class Inst3’s aggregate management fee for the fiscal year ended March 31, 2022).

Columbia Adaptive Retirement 2060 Fund

The information in the table below reflects the fees and expenses for each Fund for the semiannual period ended September 30, 2022 (annualized) and the pro forma projected expenses for each Fund for the semiannual period ended September 30, 2022 (annualized).

Current Fees and Expenses

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

you invest $10,000 in the Fund for the periods indicated,

your investment has a 5% return each year, and

the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

The waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above are reflected in Year 1 and Years 2 through 10 expense examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

Pro Forma Fees and Expenses