<Page>
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, D.C. 20549
FORM N-CSR
CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES
Investment Company Act File Number: 811-10597
---------
Tax-Managed Mid-Cap Core Portfolio
----------------------------------
(Exact Name of Registrant as Specified in Charter)
The Eaton Vance Building, 255 State Street, Boston, Massachusetts 02109
-----------------------------------------------------------------------
(Address of Principal Executive Offices)
Alan R. Dynner
The Eaton Vance Building, 255 State Street, Boston, Massachusetts 02109
-----------------------------------------------------------------------
(Name and Address of Agent for Services)
(617) 482-8260
--------------
(Registrant's Telephone Number)
October 31
----------
Date of Fiscal Year End
October 31, 2004
----------------
Date of Reporting Period
<Page>
ITEM 1. REPORTS TO STOCKHOLDERS
<Page>
TAX-MANAGED MID-CAP CORE PORTFOLIO as of October 31, 2004
PORTFOLIO OF INVESTMENTS
COMMON STOCKS -- 98.5%
<Table>
<Caption>
SECURITY SHARES VALUE
- ------------------------------------------------------------------------------------------
ADVERTISING AGENCIES -- 2.1%
Omnicom Group 17,500 $ 1,380,750
- ------------------------------------------------------------------------------------------
$ 1,380,750
- ------------------------------------------------------------------------------------------
AEROSPACE / DEFENSE -- 1.0%
Engineered Support Systems, Inc. 14,200 $ 682,168
- ------------------------------------------------------------------------------------------
$ 682,168
- ------------------------------------------------------------------------------------------
APPLICATIONS SOFTWARE -- 1.5%
Jack Henry & Associates, Inc. Class A 54,800 $ 1,021,472
- ------------------------------------------------------------------------------------------
$ 1,021,472
- ------------------------------------------------------------------------------------------
AUTO PARTS AND EQUIPMENT -- 1.2%
Gentex Corp. 25,000 $ 825,250
- ------------------------------------------------------------------------------------------
$ 825,250
- ------------------------------------------------------------------------------------------
AUTOMOBILES -- 1.1%
Winnebago Industries 24,000 $ 753,600
- ------------------------------------------------------------------------------------------
$ 753,600
- ------------------------------------------------------------------------------------------
BANKS-REGIONAL -- 1.8%
City National Corp. 18,000 $ 1,240,200
- ------------------------------------------------------------------------------------------
$ 1,240,200
- ------------------------------------------------------------------------------------------
BROADCASTING AND RADIO -- 3.4%
Cox Radio, Inc. Class A(1) 69,920 $ 1,111,728
Radio One, Inc., Class D(1) 79,190 1,163,301
- ------------------------------------------------------------------------------------------
$ 2,275,029
- ------------------------------------------------------------------------------------------
BUILDING PRODUCTS -- 1.8%
Valspar Corp. 25,500 $ 1,189,830
- ------------------------------------------------------------------------------------------
$ 1,189,830
- ------------------------------------------------------------------------------------------
BUSINESS SERVICES-MISCELLANEOUS -- 5.1%
ChoicePoint, Inc.(1) 32,966 $ 1,372,375
Fiserv, Inc.(1) 31,200 1,108,848
SEI Investments Co. 26,800 964,532
- ------------------------------------------------------------------------------------------
$ 3,445,755
- ------------------------------------------------------------------------------------------
CHEMICALS -- 2.0%
Air Products and Chemicals, Inc. 25,600 $ 1,361,408
- ------------------------------------------------------------------------------------------
$ 1,361,408
- ------------------------------------------------------------------------------------------
COMPUTER SERVICES -- 1.2%
SunGard Data Systems, Inc.(1) 30,000 $ 794,700
- ------------------------------------------------------------------------------------------
$ 794,700
- ------------------------------------------------------------------------------------------
COSMETICS & TOILETRIES -- 1.4%
Alberto-Culver Co. 20,750 $ 930,845
- ------------------------------------------------------------------------------------------
$ 930,845
- ------------------------------------------------------------------------------------------
DISTRIBUTION / WHOLESALE -- 2.7%
CDW Corp. 29,200 $ 1,811,276
- ------------------------------------------------------------------------------------------
$ 1,811,276
- ------------------------------------------------------------------------------------------
ELECTRICAL EQUIPMENT -- 2.0%
Cooper Industries Ltd. Class A 21,100 $ 1,348,290
- ------------------------------------------------------------------------------------------
$ 1,348,290
- ------------------------------------------------------------------------------------------
ELECTRONICS-EQUIPMENT / INSTRUMENTS -- 4.2%
Amphenol Corp. Class A(1) 47,400 $ 1,627,242
National Instruments Corp. 43,450 1,196,178
- ------------------------------------------------------------------------------------------
$ 2,823,420
- ------------------------------------------------------------------------------------------
FINANCE-INVESTMENT MANAGEMENT -- 7.5%
Affiliated Managers Group, Inc.(1) 26,000 $ 1,451,840
Ambac Financial Group, Inc. 14,700 1,147,482
Franklin Resources, Inc. 15,400 933,548
Legg Mason, Inc. 23,400 1,490,814
- ------------------------------------------------------------------------------------------
$ 5,023,684
- ------------------------------------------------------------------------------------------
FOOD-WHOLESALE / DISTRIBUTION -- 2.4%
Dean Foods Co.(1) 25,000 $ 746,250
Performance Food Group Co.(1) 36,800 855,968
- ------------------------------------------------------------------------------------------
$ 1,602,218
- ------------------------------------------------------------------------------------------
GAS DISTRIBUTION -- 1.9%
Piedmont Natural Gas Co., Inc. 27,600 $ 1,256,628
- ------------------------------------------------------------------------------------------
$ 1,256,628
- ------------------------------------------------------------------------------------------
</Table>
See notes to financial statements
16
<Page>
<Table>
<Caption>
SECURITY SHARES VALUE
- ------------------------------------------------------------------------------------------
HEALTHCARE SERVICES -- 1.3%
Express Scripts, Inc.(1) 14,000 $ 896,000
- ------------------------------------------------------------------------------------------
$ 896,000
- ------------------------------------------------------------------------------------------
HOUSEHOLD PRODUCTS -- 2.7%
Mohawk Industries, Inc.(1) 21,400 $ 1,820,712
- ------------------------------------------------------------------------------------------
$ 1,820,712
- ------------------------------------------------------------------------------------------
INSURANCE -- 2.3%
Ace Ltd. 21,700 $ 825,902
Nationwide Financial Services, Inc., Class A 20,200 698,920
- ------------------------------------------------------------------------------------------
$ 1,524,822
- ------------------------------------------------------------------------------------------
INSURANCE BROKERS -- 0.9%
Arthur J. Gallagher & Co., Inc. 22,220 $ 624,382
- ------------------------------------------------------------------------------------------
$ 624,382
- ------------------------------------------------------------------------------------------
INVESTMENT SERVICES -- 2.2%
A.G. Edwards, Inc. 40,400 $ 1,464,904
- ------------------------------------------------------------------------------------------
$ 1,464,904
- ------------------------------------------------------------------------------------------
MANUFACTURING -- 3.4%
Dover Corp. 26,100 $ 1,024,947
Pentair, Inc. 33,200 1,241,016
- ------------------------------------------------------------------------------------------
$ 2,265,963
- ------------------------------------------------------------------------------------------
MEDICAL-HOSPITALS -- 1.2%
Health Management Associates, Inc. Class A 40,600 $ 838,796
- ------------------------------------------------------------------------------------------
$ 838,796
- ------------------------------------------------------------------------------------------
MEDICAL DEVICES -- 1.8%
Varian Medical Systems, Inc.(1) 29,700 $ 1,192,455
- ------------------------------------------------------------------------------------------
$ 1,192,455
- ------------------------------------------------------------------------------------------
MEDICAL PRODUCTS -- 6.5%
Biomet, Inc. 15,940 $ 744,079
C.R. Bard, Inc. 18,500 1,050,800
Patterson Companies, Inc.(1) 27,800 1,042,500
Renal Care Group, Inc.(1) 24,750 781,110
Respironics, Inc.(1) 15,000 766,350
- ------------------------------------------------------------------------------------------
$ 4,384,839
- ------------------------------------------------------------------------------------------
MEDICAL SERVICES / SUPPLIES -- 1.4%
DENTSPLY International, Inc. 17,800 $ 925,778
- ------------------------------------------------------------------------------------------
$ 925,778
- ------------------------------------------------------------------------------------------
MULTI-UTILITIES -- 1.9%
Questar Corp. 26,700 $ 1,281,600
- ------------------------------------------------------------------------------------------
$ 1,281,600
- ------------------------------------------------------------------------------------------
OFFICE ELECTRONICS / TECHNOLOGY -- 1.9%
Zebra Technologies Corp. Class A(1) 23,775 $ 1,259,837
- ------------------------------------------------------------------------------------------
$ 1,259,837
- ------------------------------------------------------------------------------------------
OIL AND GAS-EQUIPMENT AND SERVICES -- 1.5%
National-Oilwell, Inc.(1) 29,700 $ 1,001,187
- ------------------------------------------------------------------------------------------
$ 1,001,187
- ------------------------------------------------------------------------------------------
OIL AND GAS-EXPLORATION AND PRODUCTION -- 6.4%
Apache Corp. 22,550 $ 1,143,285
EOG Resources, Inc. 14,000 931,840
Newfield Exploration Co.(1) 21,100 1,228,020
Pogo Producing Co. 21,200 972,020
- ------------------------------------------------------------------------------------------
$ 4,275,165
- ------------------------------------------------------------------------------------------
PERSONAL PRODUCTS -- 0.9%
Estee Lauder Cos., Inc. (The), Class A 14,500 $ 622,775
- ------------------------------------------------------------------------------------------
$ 622,775
- ------------------------------------------------------------------------------------------
PRINTING AND BUSINESS PRODUCTS -- 1.6%
Avery Dennison Corp. 17,600 $ 1,070,784
- ------------------------------------------------------------------------------------------
$ 1,070,784
- ------------------------------------------------------------------------------------------
PUBLISHING -- 1.7%
E.W. Scripps Co. 23,400 $ 1,116,648
- ------------------------------------------------------------------------------------------
$ 1,116,648
- ------------------------------------------------------------------------------------------
RETAIL-DISCOUNT -- 1.3%
Family Dollar Stores, Inc. 30,200 $ 892,410
- ------------------------------------------------------------------------------------------
$ 892,410
- ------------------------------------------------------------------------------------------
</Table>
See notes to financial statements
17
<Page>
<Table>
<Caption>
SECURITY SHARES VALUE
- ------------------------------------------------------------------------------------------
RETAIL-RESTAURANTS -- 2.2%
Brinker International, Inc.(1) 20,500 $ 662,150
Sonic Corp.(1) 29,600 806,008
- ------------------------------------------------------------------------------------------
$ 1,468,158
- ------------------------------------------------------------------------------------------
RETAIL-SPECIALTY AND APPAREL -- 2.0%
Bed Bath and Beyond, Inc.(1) 33,300 $ 1,358,307
- ------------------------------------------------------------------------------------------
$ 1,358,307
- ------------------------------------------------------------------------------------------
SEMICONDUCTORS & SEMICONDUCTOR EQUIPMENT -- 2.0%
Microchip Technology, Inc. 43,350 $ 1,311,338
- ------------------------------------------------------------------------------------------
$ 1,311,338
- ------------------------------------------------------------------------------------------
SPECIALTY CHEMICALS AND MATERIALS -- 1.6%
Ecolab, Inc. 31,500 $ 1,066,275
- ------------------------------------------------------------------------------------------
$ 1,066,275
- ------------------------------------------------------------------------------------------
TELECOMMUNICATIONS -- 1.4%
CenturyTel, Inc. 29,000 $ 930,610
- ------------------------------------------------------------------------------------------
$ 930,610
- ------------------------------------------------------------------------------------------
TRANSPORTATION -- 4.1%
C.H. Robinson Worldwide, Inc. 27,900 $ 1,504,926
Expeditors International of Washington, Inc. 22,100 1,261,910
- ------------------------------------------------------------------------------------------
$ 2,766,836
- ------------------------------------------------------------------------------------------
TOTAL COMMON STOCKS
(IDENTIFIED COST, $56,581,717) $ 66,127,104
- ------------------------------------------------------------------------------------------
TOTAL INVESTMENTS -- 98.5%
(IDENTIFIED COST, $56,581,717) $ 66,127,104
- ------------------------------------------------------------------------------------------
OTHER ASSETS, LESS LIABILITIES -- 1.5% $ 1,002,830
- ------------------------------------------------------------------------------------------
NET ASSETS -- 100.0% $ 67,129,934
- ------------------------------------------------------------------------------------------
</Table>
(1) Non-income producing security.
See notes to financial statements
18
<Page>
TAX-MANAGED MID-CAP CORE PORTFOLIO as of October 31, 2004
FINANCIAL STATEMENTS
STATEMENT OF ASSETS AND LIABILITIES
AS OF OCTOBER 31, 2004
<Table>
ASSETS
Investments, at value (identified cost, $56,581,717) $ 66,127,104
Cash 828,523
Receivable for investments sold 984,827
Dividends and interest receivable 15,449
- ------------------------------------------------------------------------------------------
TOTAL ASSETS $ 67,955,903
- ------------------------------------------------------------------------------------------
LIABILITIES
Payable for investments purchased $ 790,250
Payable to affiliate for Trustees' fees 1,570
Accrued expenses 34,149
- ------------------------------------------------------------------------------------------
TOTAL LIABILITIES $ 825,969
- ------------------------------------------------------------------------------------------
NET ASSETS APPLICABLE TO INVESTORS' INTEREST IN PORTFOLIO $ 67,129,934
- ------------------------------------------------------------------------------------------
SOURCES OF NET ASSETS
Net proceeds from capital contributions and withdrawals $ 57,584,547
Net unrealized appreciation (computed on the basis of identified cost) 9,545,387
- ------------------------------------------------------------------------------------------
TOTAL $ 67,129,934
- ------------------------------------------------------------------------------------------
</Table>
STATEMENT OF OPERATIONS
FOR THE YEAR ENDED
OCTOBER 31, 2004
<Table>
INVESTMENT INCOME
Dividends $ 453,404
Interest 4,573
- ------------------------------------------------------------------------------------------
TOTAL INVESTMENT INCOME $ 457,977
- ------------------------------------------------------------------------------------------
EXPENSES
Investment adviser fee $ 470,752
Trustees' fees and expenses 5,182
Custodian fee 46,750
Legal and accounting services 24,325
Miscellaneous 3,029
- ------------------------------------------------------------------------------------------
TOTAL EXPENSES $ 550,038
- ------------------------------------------------------------------------------------------
Deduct --
Reduction of investment adviser fee $ 2,466
- ------------------------------------------------------------------------------------------
TOTAL EXPENSE REDUCTIONS $ 2,466
- ------------------------------------------------------------------------------------------
NET EXPENSES $ 547,572
- ------------------------------------------------------------------------------------------
NET INVESTMENT LOSS $ (89,595)
- ------------------------------------------------------------------------------------------
REALIZED AND UNREALIZED GAIN (LOSS)
Net realized gain (loss) --
Investment transactions (identified cost basis) $ 914,226
- ------------------------------------------------------------------------------------------
NET REALIZED GAIN $ 914,226
- ------------------------------------------------------------------------------------------
Change in unrealized appreciation (depreciation) --
Investments (identified cost basis) $ 2,644,478
- ------------------------------------------------------------------------------------------
NET CHANGE IN UNREALIZED APPRECIATION (DEPRECIATION) $ 2,644,478
- ------------------------------------------------------------------------------------------
NET REALIZED AND UNREALIZED GAIN $ 3,558,704
- ------------------------------------------------------------------------------------------
NET INCREASE IN NET ASSETS FROM OPERATIONS $ 3,469,109
- ------------------------------------------------------------------------------------------
</Table>
See notes to financial statements
19
<Page>
STATEMENTS OF CHANGES IN NET ASSETS
<Table>
<Caption>
INCREASE (DECREASE) YEAR ENDED YEAR ENDED
IN NET ASSETS OCTOBER 31, 2004 OCTOBER 31, 2003
- -------------------------------------------------------------------------------------------------
From operations --
Net investment loss $ (89,595) $ (64,901)
Net realized gain (loss) from
investment transactions 914,226 (927,356)
Net change in unrealized
appreciation (depreciation)
of investments 2,644,478 8,290,032
- -------------------------------------------------------------------------------------------------
NET INCREASE IN NET ASSETS FROM OPERATIONS $ 3,469,109 $ 7,297,775
- -------------------------------------------------------------------------------------------------
Capital transactions --
Contributions $ 21,164,553 $ 25,984,940
Withdrawals (3,615,999) (4,319,456)
- -------------------------------------------------------------------------------------------------
NET INCREASE IN NET ASSETS FROM
CAPITAL TRANSACTIONS $ 17,548,554 $ 21,665,484
- -------------------------------------------------------------------------------------------------
NET INCREASE IN NET ASSETS $ 21,017,663 $ 28,963,259
- -------------------------------------------------------------------------------------------------
NET ASSETS
At beginning of year $ 46,112,271 $ 17,149,012
- -------------------------------------------------------------------------------------------------
AT END OF YEAR $ 67,129,934 $ 46,112,271
- -------------------------------------------------------------------------------------------------
</Table>
See notes to financial statements
20
<Page>
SUPPLEMENTARY DATA
<Table>
<Caption>
YEAR ENDED OCTOBER 31,
----------------------------- PERIOD ENDED
2004 2003 OCTOBER 31, 2002(1)
- -----------------------------------------------------------------------------------------------------------------
RATIOS/SUPPLEMENTAL DATA+
Ratios (As a percentage of average daily net assets):
Net expenses 0.93% 0.99% 1.68%(2)
Net investment loss (0.15)% (0.22)% (0.81)%(2)
Portfolio Turnover 42% 50% 13%
- -----------------------------------------------------------------------------------------------------------------
TOTAL RETURN(3) 6.43% 25.97% (14.72)%
- -----------------------------------------------------------------------------------------------------------------
NET ASSETS, END OF YEAR (000'S OMITTED) $ 67,130 $ 46,112 $ 17,149
- -----------------------------------------------------------------------------------------------------------------
</Table>
+ The operating expenses of the Portfolio reflect a reduction of the investment
adviser fee. Had such action not been taken, the ratios would have been as
follows:
<Table>
Ratios (As a percentage of average daily net assets):
Expenses 0.93% -- --
Net investment loss (0.15)% -- --
- -----------------------------------------------------------------------------------------------------------------
</Table>
(1) For the period from the start of business, March 1, 2002, to October 31,
2002.
(2) Annualized.
(3) Total return is not computed on an annualized basis.
See notes to financial statements
21
<Page>
TAX-MANAGED MID-CAP CORE PORTFOLIO as of October 31, 2004
NOTES TO FINANCIAL STATEMENTS
1 SIGNIFICANT ACCOUNTING POLICIES
Tax-Managed Mid-Cap Core Portfolio (the Portfolio) is registered under the
Investment Company Act of 1940, as amended, as a diversified open-end
management investment company. The Portfolio, which was organized as a trust
under the laws of the State of New York on December 10, 2001, seeks to
achieve long-term, after-tax returns by investing in a diversified portfolio
of common stocks of mid-cap companies. The Declaration of Trust permits the
Trustees to issue interests in the Portfolio. At October 31, 2004, the Eaton
Vance Tax-Managed Mid-Cap Core Fund and the Eaton Vance Tax-Managed Equity
Asset Allocation Fund held 33.4% and 66.4% interests in the Portfolio,
respectively. The following is a summary of significant accounting policies
consistently followed by the Portfolio in the preparation of its financial
statements. The policies are in conformity with accounting principles
generally accepted in the United States of America.
A INVESTMENT VALUATION -- Securities listed on a U.S. securities exchange
generally are valued at the last sale price on the day of valuation or, if no
sales took place on such date, at the mean between the closing bid and asked
prices therefore on the exchange where such securities are principally
traded. Equity securities listed on the NASDAQ National Market System
generally are valued at the official NASDAQ closing price. Unlisted or listed
securities for which closing sales prices or closing quotations are not
available are valued at the mean between the latest available bid and asked
prices, or, in the case of preferred equity securities that are not listed or
traded in the over-the-counter market, by an independent pricing service.
Exchange-traded options are valued at the last sale price for the day of
valuation as quoted on the principal exchange or board of trade on which the
options are traded or, in the absence of sales on such date, at the mean
between the latest bid and asked prices therefore. Futures positions on
securities and currencies generally are valued at closing settlement prices.
Short-term debt securities with a remaining maturity of 60 days or less are
valued at amortized cost. If short-term debt securities were acquired with a
remaining maturity of more than 60 days, their amortized cost value will be
based on their value on the sixty-first day prior to maturity. Other fixed
income and debt securities, including listed securities and securities for
which price quotations are available, will normally be valued on the basis of
valuations furnished by a pricing service. The daily valuation of foreign
securities generally is determined as of the close of trading on the
principal exchange on which such securities trade. Events occurring after the
close of trading on foreign exchanges may result in adjustments to the
valuation of foreign securities to more accurately reflect their fair value
as of the close of regular trading on the New York Stock Exchange. The
Portfolio may rely on an independent fair valuation service in adjusting the
valuations of foreign securities. Foreign securities and currencies are
valued in U.S. dollars, based on foreign currency exchange rate quotations
supplied by an independent quotation service. Investments held by the
Portfolio for which valuations or market quotations are unavailable are
valued at fair value using methods determined in good faith by or at the
direction of the Trustees of the Portfolio considering relevant factors, data
and information including the market value of freely tradable securities of
the same class in the principal market on which such securities are normally
traded.
B INCOME -- Dividend income is recorded on the ex-dividend date for dividends
received in cash and/or securities. However, if the ex-dividend date has
passed, certain dividends from foreign securities are recorded as the
Portfolio is informed of the ex-dividend date. Interest income is recorded on
the accrual basis.
C INCOME TAXES -- The Portfolio is treated as a partnership for federal tax
purposes. No provision is made by the Portfolio for federal or state taxes on
any taxable income of the Portfolio because each investor in the Portfolio is
ultimately responsible for the payment of any taxes on its share of taxable
income. Since the Portfolio's investors include regulated investment
companies that invest all or substantially all of their assets in the
Portfolio, the Portfolio normally must satisfy the applicable source of
income and diversification requirements (under the Internal Revenue Code) in
order for its investors to satisfy them. The Portfolio will allocate at least
annually among its investors each investor's distributive share of the
Portfolio's net investment income, net realized capital gains, and any other
items of income, gain, loss, deduction or credit.
D EXPENSE REDUCTION -- Investors Bank & Trust Company (IBT) serves as
custodian to the Portfolio. Pursuant to the custodian agreement, IBT receives
a fee reduced by credits which are determined based on the average daily cash
balances the Portfolio maintains with IBT. All credit balances used to reduce
the Portfolio's custodian fees are reported as a reduction of total expenses
on the Statement of Operations.
E FINANCIAL FUTURES CONTRACT -- Upon entering a financial futures contract,
the Portfolio is required to deposit either in cash or securities an amount
(initial margin) equal to a certain percentage of the purchase price
22
<Page>
indicated in the financial futures contract. Subsequent payments are made or
received by the Portfolio (margin maintenance) each day, dependent on daily
fluctuations in the value of the underlying security, and are recorded for
book purposes as unrealized gains or losses by the Portfolio. The Portfolio's
investment in financial futures contracts is designed to hedge against
anticipated future changes in price of current or anticipated Portfolio
positions. Should prices move unexpectedly, the Portfolio may not achieve the
anticipated benefits of the financial futures contracts and may realize a
loss.
F PUT OPTIONS -- Upon the purchase of a put option by the Portfolio, the
premium paid is recorded as an investment, the value of which is
marked-to-market daily. When a purchased option expires, the Portfolio will
realize a loss in the amount of the cost of the option. When the Portfolio
enters into a closing sale transaction, the Portfolio will realize a gain or
loss depending on whether the sales proceeds from the closing sale
transaction are greater or less than the cost of the option. When the
Portfolio exercises a put option, settlement is made in cash. The risk
associated with purchasing options is limited to the premium originally paid.
G SECURITIES SOLD SHORT -- The Portfolio may sell a security short if it owns
at least an equal amount of the security sold short or another security
convertible or exchangeable for an equal amount of the security sold short.
Such transactions are done in anticipation of a decline in the market price
of the securities or in order to hedge portfolio positions. The Portfolio
will generally borrow the security sold in order to make delivery to the
buyer. Upon executing the transaction, the Portfolio records the proceeds as
deposits with brokers in the Statement of Assets and Liabilities and
establishes an offsetting payable for securities sold short for the
securities due on settlement. The proceeds are retained by the broker as
collateral for the short position. The liability is marked-to-market and the
Portfolio is required to pay the lending broker any dividend or interest
income earned while the short position is open. A gain or loss is recorded
when the security is delivered to the broker. The Portfolio may recognize a
loss on the transaction if the market value of the securities sold increases
before the securities are delivered.
H FOREIGN CURRENCY TRANSLATION -- Investment valuations, other assets and
liabilities initially expressed in foreign currencies are converted each
business day into U.S. dollars based upon current exchange rates. Purchases
and sales of foreign investment securities and income and expenses are
converted into U.S. dollars based upon currency exchange rates prevailing on
the respective dates of such transactions. Recognized gains or losses on
investment transactions attributable to foreign currency exchange rates are
recorded for financial statement purposes as net realized gains and losses on
investments. That portion of unrealized gains and losses on investments that
results from fluctuations in foreign currency exchange rates is not
separately disclosed.
I USE OF ESTIMATES -- The preparation of the financial statements in
conformity with accounting principles generally accepted in the United States
of America requires management to make estimates and assumptions that affect
the reported amounts of assets and liabilities at the date of the financial
statements and the reported amounts of income and expense during the
reporting period. Actual results could differ from those estimates.
J OTHER -- Investment transactions are accounted for on a trade date basis.
K INDEMNIFICATIONS -- Under the Portfolio's organizational documents, its
officers and Trustees may be indemnified against certain liabilities and
expenses arising out of the performance of their duties to the Portfolio.
Interestholders in the Portfolio are jointly and severally liable for the
liabilities and obligations of the Portfolio in the event that the Portfolio
fails to satisfy such liabilities and obligations; provided, however, that,
to the extent assets are available in the Portfolio, the Portfolio may, under
certain circumstances, indemnify interestholders from and against any claim
or liability to which such holder may become subject by reason of being or
having been an interestholder in the Portfolio. Additionally, in the normal
course of business, the Portfolio enters into agreements with service
providers that may contain indemnification clauses. The Portfolio's maximum
exposure under these arrangements is unknown as this would involve future
claims that may be made against the Portfolio that have not yet occurred.
2 INVESTMENT ADVISER FEE AND OTHER TRANSACTIONS WITH AFFILIATES
The investment adviser fee is earned by Boston Management and Research (BMR),
a wholly-owned subsidiary of Eaton Vance Management (EVM), as compensation
for management and investment advisory services rendered to the Portfolio.
Under the advisory agreement, BMR receives a monthly advisory fee equal to
0.80% annually of the average daily net assets of the Portfolio up to $500
million, and at reduced rates as daily net assets exceed that level. For the
year ended October 31, 2004, the advisory fee amounted to $470,752. BMR has
agreed to reduce the investment
23
<Page>
adviser fee by an amount equal to that portion of commissions paid to broker
dealers in execution of Portfolio transactions that is consideration for
third-party research services. For the period from May 1, 2004, to October
31, 2004, BMR waived $2,466 of its advisory fee. Pursuant to a sub-advisory
agreement, BMR has delegated the investment management of the Portfolio to
Atlanta Capital Management Company, LLC (Atlanta Capital), a majority-owned
subsidiary of Eaton Vance. BMR pays Atlanta Capital a monthly fee for
sub-advisory services provided to the Portfolio equal to 0.55% annually of
the average daily net assets up to $500 million, and at reduced rates as
daily net assets exceed that level. Except for Trustees of the Portfolio who
are not members of EVM's or BMR's organization, officers and Trustees receive
remuneration for their services to the Portfolio out of the investment
adviser fee. Trustees of the Portfolio who are not affiliated with BMR may
elect to defer receipt of all or a percentage of their annual fees in
accordance with the terms of the Trustees Deferred Compensation Plan. For the
year ended October 31, 2004, no significant amounts have been deferred.
Certain officers and Trustees of the Portfolio are officers of the above
organizations.
3 INVESTMENT TRANSACTIONS
Purchases and sales of investments, other than short-term obligations,
aggregated $42,264,998 and $24,547,600, respectively, for the year ended
October 31, 2004.
4 FEDERAL INCOME TAX BASIS OF UNREALIZED APPRECIATION (DEPRECIATION)
The cost and unrealized appreciation (depreciation) in value of the
investments owned at October 31, 2004, as computed on a federal income tax
basis, were as follows:
<Table>
AGGREGATE COST $ 56,882,684
--------------
Gross unrealized appreciation $ 10,678,194
Gross unrealized depreciation (1,433,774)
--------------
NET UNREALIZED APPRECIATION $ 9,244,420
--------------
</Table>
5 FINANCIAL INSTRUMENTS
The Portfolio may trade in financial instruments with off-balance sheet risk
in the normal course of its investing activities to assist in managing
exposure to various market risks. These financial instruments include written
options and financial futures contracts and may involve, to a varying degree,
elements of risk in excess of the amounts recognized for financial statement
purposes.
The notional or contractual amounts of these instruments represent the
investment the Portfolio has in particular classes of financial instruments
and does not necessarily represent the amounts potentially subject to risk.
The measurement of the risks associated with these instruments is meaningful
only when all related and offsetting transactions are considered. The
Portfolio did not have any open obligations under these financial instruments
at October 31, 2004.
6 LINE OF CREDIT
The Portfolio participates with other portfolios and funds managed by BMR and
EVM and its affiliates in a $150 million unsecured line of credit agreement
with a group of banks. Borrowings will be made by the Portfolio solely to
facilitate the handling of unusual and/or unanticipated short-term cash
requirements. Interest is charged to each participating portfolio or fund
based on its borrowings at an amount above either the Eurodollar rate or
Federal Funds rate. In addition, a fee computed at an annual rate of 0.10% on
the daily unused portion of the line of credit is allocated among the
participating portfolios and funds at the end of each quarter. The Portfolio
did not have any significant borrowings or allocated fees for the year ended
October 31, 2004.
24
<Page>
TAX-MANAGED MID-CAP CORE PORTFOLIO as of October 31, 2004
REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM
TO THE TRUSTEES AND INVESTORS OF TAX-MANAGED MID-CAP CORE PORTFOLIO:
We have audited the accompanying statement of assets and liabilities, including
the portfolio of investments, of Tax-Managed Mid-Cap Core Portfolio (the
Portfolio) as of October 31, 2004, and the related statement of operations for
the year then ended, the statement of changes in net assets for each of the two
years in the period then ended and the supplementary data for each of the two
years in the period then ended, and the period from the start of business, March
1, 2002, to October 31, 2002. These financial statements and supplementary data
are the responsibility of the Portfolio's management. Our responsibility is to
express an opinion on these financial statements and supplementary data based on
our audit.
We conducted our audit in accordance with standards of the Public Company
Accounting Oversight Board (United States). Those standards require that we plan
and perform the audit to obtain reasonable assurance about whether the financial
statements and supplementary data are free of material misstatement. An audit
includes examining, on a test basis, evidence supporting the amounts and
disclosures in the financial statements. Our procedures included confirmation of
securities held as of October 31, 2004 by correspondence with the custodian and
brokers; where replies were not received from brokers, we performed other
auditing procedures. An audit also includes assessing the accounting principles
used and significant estimates made by management, as well as evaluating the
overall financial statement presentation. We believe that our audit provides a
reasonable basis for our opinion.
In our opinion, such financial statements and supplementary data present fairly,
in all material respects, the financial position of Tax-Managed Mid-Cap Core
Portfolio at October 31, 2004, the results of its operations for the year then
ended, and the changes in its net assets and the supplementary data for the
respective stated periods in conformity with accounting principles generally
accepted in the United States of America.
DELOITTE & TOUCHE LLP
Boston, Massachusetts
December 22, 2004
25
<Page>
EATON VANCE TAX-MANAGED MID-CAP CORE FUND
MANAGEMENT AND ORGANIZATION
FUND MANAGEMENT. The Trustees of Eaton Vance Mutual Funds Trust (the Trust) and
Tax-Managed Mid-Cap Core Portfolio (the Portfolio) are responsible for the
overall management and supervision of the Trust's and Portfolio's affairs. The
Trustees and officers of the Trust and the Portfolio are listed below. Except as
indicated, each individual has held the office shown or other offices in the
same company for the last five years. Trustees and officers of the Trust and the
Portfolio hold indefinite terms of office. The "noninterested Trustees" consist
of those Trustees who are not "interested persons" of the Trust and the
Portfolio, as that term is defined under the 1940 Act. The business address of
each Trustee and officer is The Eaton Vance Building, 255 State Street, Boston,
Massachusetts 02109. As used below, "EVC" refers to Eaton Vance Corp., "EV"
refers to Eaton Vance, Inc., "EVM" refers to Eaton Vance Management, "BMR"
refers to Boston Management and Research, "EVD" refers to Eaton Vance
Distributors, Inc. and "Atlanta Capital" refers to Atlanta Capital Management
Company, LLC. EVC and EV are the corporate parent and trustee, respectively, of
EVM and BMR. EVD is the Fund's principal underwriter, the Portfolio's placement
agent and a wholly-owned subsidiary of EVM.
<Table>
<Caption>
POSITION(S) TERM OF NUMBER OF PORTFOLIOS
WITH THE OFFICE AND IN FUND COMPLEX
NAME AND TRUST AND LENGTH OF PRINCIPAL OCCUPATION(S) OVERSEEN BY
DATE OF BIRTH THE PORTFOLIO SERVICE DURING PAST FIVE YEARS TRUSTEE(1) OTHER DIRECTORSHIPS HELD
- ------------------------------------------------------------------------------------------------------------------------------------
INTERESTED TRUSTEE
James B. Hawkes Trustee of the Trustee of the Chairman, President and 192 Director of EVC
11/9/41 Trust; Trustee Trust since Chief Executive Officer
and President of 1991; Trustee of BMR, EVC, EVM and
the Portfolio and President EV; Director of EV;
of the Vice President and
Portfolio Director of EVD.
since 2001 Trustee and/or officer
of 192 registered
investment companies in
the Eaton Vance Fund
Complex. Mr. Hawkes is
an interested person
because of his
positions with BMR,
EVM, EVC and EV, which
are affiliates of the
Trust and the
Portfolio.
NONINTERESTED TRUSTEE(S)
Samuel L. Hayes, III Trustee Trustee of the Jacob H. Schiff 192 Director of Tiffany &
2/23/35 Trust since Professor of Investment Co. (specialty retailer)
1986; of the Banking Emeritus, and Telect, Inc.
Portfolio Harvard University (telecommunication
since 2001 Graduate School of services company)
Business
Administration.
William H. Park Trustee Since 2003 President and Chief 192 None
9/19/47 Executive Officer,
Prizm Capital
Management, LLC
(investment management
firm) (since 2002).
Executive Vice
President and Chief
Financial Officer,
United Asset Management
Corporation ( a holding
company owning
institutional
investment management
firms) (1982-2001).
Ronald A. Pearlman Trustee Since 2003 Professor of Law, 192 None
7/10/40 Georgetown University
Law Center (since
1999). Tax Partner,
Covington & Burling,
Washington, DC
(1991-2000).
</Table>
26
<Page>
<Table>
<Caption>
POSITION(S) TERM OF NUMBER OF PORTFOLIOS
WITH THE OFFICE AND IN FUND COMPLEX
NAME AND TRUST AND LENGTH OF PRINCIPAL OCCUPATION(S) OVERSEEN BY
DATE OF BIRTH THE PORTFOLIO SERVICE DURING PAST FIVE YEARS TRUSTEE(1) OTHER DIRECTORSHIPS HELD
- ------------------------------------------------------------------------------------------------------------------------------------
NONINTERESTED TRUSTEE(S)
(CONTINUED)
Norton H. Reamer Trustee Trustee of the President, Chief 192 None
9/21/35 Trust since Executive Officer and a
1986; of the Director of Asset
Portfolio Management Finance
since 2001 Corp. (a specialty
finance company serving
the investment
management industry)
(since October 2003).
President, Unicorn
Corporation (an
investment and
financial advisory
services company)
(since September 2000).
Formerly, Chairman,
Hellman, Jordan
Management Co., Inc.
(an investment
management company)
(2000-2003). Formerly,
Advisory Director of
Berkshire Capital
Corporation (investment
banking firm)
(2002-2003). Formerly
Chairman of the Board,
United Asset Management
Corporation (a holding
company owning
institutional
investment management
firms) and Chairman,
President and Director,
UAM Funds (mutual
funds) (1980-2000).
Lynn A. Stout Trustee Trustee of the Professor of Law, 192 None
9/14/57 Trust since University of
1998; of the California at Los
Portfolio Angeles School of Law
since 2001 (since July 2001).
Formerly, Professor of
Law, Georgetown
University Law Center.
</Table>
PRINCIPAL OFFICERS WHO ARE NOT TRUSTEES
<Table>
<Caption>
POSITION(S) TERM OF
WITH THE OFFICE AND
NAME AND TRUST AND LENGTH OF PRINCIPAL OCCUPATION(S)
DATE OF BIRTH THE PORTFOLIO SERVICE DURING PAST FIVE YEARS
- ------------------------------------------------------------------------------------------------------------------------------------
Thomas E. Faust Jr. President of the Trust; President of the Trust since Executive Vice President of EVM, BMR, EVC and EV;
5/31/58 Vice President of the 2002; Vice President of the Chief Investment Officer of EVM and BMR and
Portfolio Portfolio since 2001 Director of EVC. Chief Executive Officer of Belair
Capital Fund LLC, Belcrest Capital Fund LLC,
Belmar Capital Fund LLC, Belport Capital Fund LLC
and Belrose Capital Fund LLC (private investment
companies sponsored by EVM). Officer of 55
registered investment companies managed by EVM or
BMR.
William H. Ahern, Jr. Vice President of the Since 1995 Vice President of EVM and BMR. Officer of 78
7/28/59 Trust registered investment companies managed by EVM or
BMR.
Thomas J. Fetter Vice President of the Since 1997 Vice President of EVM and BMR. Officer of 124
8/20/43 Trust registered investment companies managed by EVM or
BMR.
William R. Hackney, III Vice President of the Since 2001 Managing Partner and member of the Executive
4/12/48 Portfolio Committee of Atlanta Capital. Officer of 3
registered investment companies managed by EVM or
BMR.
Michael R. Mach Vice President of the Since 1999 Vice President of EVM and BMR. Previously,
7/15/47 Trust Managing Director and Senior Analyst for Robertson
Stephens (1998-1999). Officer of 28 registered
investment companies managed by EVM or BMR.
Robert B. MacIntosh Vice President of the Since 1998 Vice President of EVM and BMR. Officer of 124
1/22/57 Trust registered investment companies managed by EVM or
BMR.
Paul J. Marshall Vice President of the Since 2001 Vice President of Atlanta Capital. Portfolio
5/2/65 Portfolio manager for Bank of America Capital Management
(1995-2000). Officer of 2 registered investment
companies managed by EVM or BMR.
Charles B. Reed Vice President of the Since 2001 Vice President of Atlanta Capital. Officer of 2
10/9/65 Portfolio registered investment companies managed by EVM or
BMR.
Duncan W. Richardson Vice President of the Since 2001 Senior Vice President and Chief Equity Investment
10/26/57 Trust Officer of EVM and BMR. Officer of 44 registered
investment companies managed by EVM or BMR.
</Table>
27
<Page>
<Table>
<Caption>
POSITION(S) TERM OF
WITH THE OFFICE AND
NAME AND TRUST AND LENGTH OF PRINCIPAL OCCUPATION(S)
DATE OF BIRTH THE PORTFOLIO SERVICE DURING PAST FIVE YEARS
- ------------------------------------------------------------------------------------------------------------------------------------
PRINCIPAL OFFICERS WHO
ARE NOT TRUSTEES
(CONTINUED)
Walter A. Row, III Vice President of the Since 2003 Director of Equity Research and a Vice President
7/20/57 Trust of EVM and BMR. Officer of 24 registered
investment companies managed by EVM or BMR.
Judith A. Saryan Vice President of the Since 2001 Vice President of EVM and BMR. Previously,
8/21/54 Trust Portfolio Manager and Equity Analyst for State
Street Global Advisers (1980-1999). Officer of 27
registered investment companies managed by EVM or
BMR.
Susan Schiff Vice President of the Since 2002 Vice President of EVM and BMR. Officer of 27
3/13/61 Trust registered investment companies managed by EVM or
BMR.
Alan R. Dynner Secretary Secretary of the Trust since Vice President, Secretary and Chief Legal Officer
10/10/40 1997; of the Portfolio since of BMR, EVM, EVD, EV and EVC. Officer of 192
2001 registered investment companies managed by EVM or
BMR.
Michelle A. Green Treasurer of the Since 2002 Vice President of EVM and BMR. Chief Financial
8/25/69 Portfolio Officer of Belair Capital Fund LLC, Belcrest
Capital Fund LLC, Belmar Capital Fund LLC, Belport
Capital Fund LLC and Belrose Capital Fund LLC
(private investment companies sponsored by EVM).
Officer of 83 registered investment companies
managed by EVM or BMR.
James L. O'Connor Treasurer of the Trust Since 1989 Vice President of BMR, EVM and EVD. Officer of 114
4/1/45 registered investment companies managed by EVM or
BMR.
Paul M. O'Neil Chief Compliance Since 2004 Vice President of EVM and BMR. Officer of 192
7/11/53 Officer registered investment companies managed by EVM or
BMR.
</Table>
(1) Includes both master and feeder funds in a master-feeder structure.
The SAI for the Fund includes additional information about the Trustees and
officers of the Fund and the Portfolio and can be obtained without charge by
calling 1-800-225-6265.
28
<Page>
ITEM 2. CODE OF ETHICS
The registrant has adopted a code of ethics applicable to its Principal
Executive Officer, Principal Financial Officer and Principal Accounting Officer.
The registrant undertakes to provide a copy of such code of ethics to any person
upon request, without charge, by calling 1-800-262-1122.
ITEM 3. AUDIT COMMITTEE FINANCIAL EXPERT
The registrant's Board has designated William H. Park, Samuel L. Hayes, III and
Norton H. Reamer, each an independent trustee, as its audit committee financial
experts. Mr. Park is a certified public accountant who is the President and
Chief Executive Officer of Prizm Capital Management, LLC (investment management
firm). Previously, he served as Executive Vice President and Chief Financial
Officer of United Asset Management Corporation ("UAM") (a holding company owning
institutional investment management firms). Mr. Hayes is the Jacob H. Schiff
Professor of Investment Banking Emeritus of the Harvard University Graduate
School of Business Administration. Mr. Reamer is the President, Chief Executive
Officer and a Director of Asset Management Finance Corp. (a specialty finance
company serving the investment management industry) and is President of Unicorn
Corporation (an investment and financial advisory services company). Formerly,
Mr. Reamer was Chairman of Hellman, Jordan Management Co., Inc. (an investment
management company) and Advisory Director of Berkshire Capital Corporation (an
investment banking firm), Chairman of the Board of UAM and Chairman, President
and Director of the UAM Funds (mutual funds).
ITEM 4. PRINCIPAL ACCOUNTANT FEES AND SERVICES
(a)-(d)
The following table presents aggregate fees billed to the registrant for the
fiscal years ended October 31, 2003, and October 31, 2004 by the registrant's
principal accountant for professional services rendered for the audit of the
registrant's annual financial statements and fees billed for other services
rendered by the principal accountant during those periods.
<Table>
<Caption>
FISCAL YEARS ENDED 10/31/03 10/31/04
- --------------------------------------------------------------------------------
Audit Fees $ 14,420 $ 19,405
Audit-Related Fees(1) $ 0 $ 0
Tax Fees(2) $ 4,000 $ 4,100
All Other Fees(3) $ 0 $ 0
-----------------------
Total $ 18,420 $ 23,505
=======================
</Table>
<Page>
(1) Audit-related fees consist of the aggregate fees billed for assurance and
related services that are reasonably related to the performance of the audit of
the registrant's financial statements and are not reported under the category of
audit fees.
(2) Tax fees consist of the aggregate fees billed for professional services
rendered by the principal accountant relating to tax compliance, tax advice, and
tax planning and specifically include fees for tax return preparation.
(3) All other fees consist of the aggregate fees billed for products and
services provided by the registrant's principal accountant other than audit,
audit-related, and tax services.
During the fiscal year ended October 31, 2004, $35,000 was billed by the
registrant's principal accountant, Deloitte and Touche LLP, for work done in
connection with its Rule 17Ad-13 Eaton Vance Management's examination of
management's assertion that it has maintained an effective internal control
structure over sub-transfer agent and registrar functions, such services being
pre-approved in accordance with Rule 2-01(c)(7)(ii) of Regulation S-X.
(e)(1) The registrant's audit committee has adopted policies and procedures
relating to the pre-approval of services provided by the registrant's principal
accountant (the "Pre-Approval Policies"). The Pre-Approval Policies establish a
framework intended to assist the audit committee in the proper discharge of its
pre-approval responsibilities. As a general matter, the Pre-Approval Policies
(i) specify certain types of audit, audit-related, tax, and other services
determined to be pre-approved by the audit committee; and (ii) delineate
specific procedures governing the mechanics of the pre-approval process,
including the approval and monitoring of audit and non-audit service fees.
Unless a service is specifically pre-approved under the Pre-Approval Policies,
it must be separately pre-approved by the audit committee.
The Pre-Approval Policies and the types of audit and non-audit services
pre-approved therein must be reviewed and ratified by the registrant's audit
committee at least annually. The registrant's audit committee maintains full
responsibility for the appointment, compensation, and oversight of the work of
the registrant's principal accountant.
(e)(2) No services described in paragraphs (b)-(d) above were approved by the
registrant's audit committee pursuant to the "de minimis exception" set forth in
Rule 2-01 (c)(7)(i)(C) of Regulation S-X.
(f) Not applicable.
(g) The following table presents (i) the aggregate non-audit fees (i.e., fees
for audit-related, tax, and other services) billed to the registrant by the
registrant's principal accountant for the last two fiscal years of the
registrant; and (ii) the aggregate non-audit fees (i.e., fees for audit-related,
tax, and other services) billed to the Eaton Vance organization by the
registrant's principal accountant for the last two fiscal years of the
registrant.
<Page>
<Table>
<Caption>
FISCAL YEARS ENDED 10/31/03 10/31/04
- --------------------------------------------------------------------------------
Registrant $ 4,000 $ 4,100
</Table>
<Page>
<Table>
Eaton Vance (1) $ 467,489 $ 340,730
</Table>
(1) The investment adviser to the registrant, as well as any of its affiliates
that provide ongoing services to the registrant, are subsidiaries of Eaton
Vance Corp.
(h) The registrant's audit committee has considered whether the provision by the
registrant's principal accountant of non-audit services to the registrant's
investment adviser and any entity controlling, controlled by, or under common
control with the adviser that provides ongoing services to the registrant that
were not pre-approved pursuant to Rule 2-01(c)(7)(ii) of Regulation S-X is
compatible with maintaining the principal accountant's independence.
ITEM 5. AUDIT COMMITTEE OF LISTED REGISTRANTS
Not required in this filing.
ITEM 6. SCHEDULE OF INVESTMENTS
Please see schedule of investments contained in the Report to Stockholders
included under Item 1 of this Form N-CSR.
ITEM 7. DISCLOSURE OF PROXY VOTING POLICIES AND PROCEDURES FOR CLOSED-END
MANAGEMENT INVESTMENT COMPANIES
Not required in this filing.
ITEM 8. PURCHASES OF EQUITY SECURITIES BY CLOSED-END MANAGEMENT INVESTMENT
COMPANY AND AFFILIATED PURCHASERS.
Not required in this filing.
ITEM 9. SUBMISSION OF MATTERS TO A VOTE OF SECURITY HOLDERS.
Effective February 9, 2004, the Governance Committee of the Board of Trustees
formalized the procedures by which a Fund's shareholders may recommend nominees
to the registrant's Board of Trustees. The Governance Committee shall, when
identifying candidates for the position of Independent Trustee, consider any
such candidate recommended by a shareholder of a Fund if such recommendation
contains sufficient background information concerning the candidate, and is
received in a sufficiently timely manner (and in any event no later than the
date specified for receipt of shareholder proposals in any applicable proxy
statement with respect to a Fund). Shareholders shall be directed to address any
such recommendations to the attention of the Governance Committee, c/o the
Secretary of the Fund.
<Page>
ITEM 10. CONTROLS AND PROCEDURES
(a) It is the conclusion of the registrant's principal executive officer and
principal financial officer that the effectiveness of the registrant's current
disclosure controls and procedures (such disclosure controls and procedures
having been evaluated within 90 days of the date of this filing) provide
reasonable assurance that the information required to be disclosed by the
registrant has been recorded, processed, summarized and reported within the time
period specified in the Commission's rules and forms and that the information
required to be disclosed by the registrant has been accumulated and communicated
to the registrant's principal executive officer and principal financial officer
in order to allow timely decisions regarding required disclosure.
(b) There have been no changes in the registrant's internal controls over
financial reporting during the period that has materially affected, or is
reasonably likely to materially affect the registrant's internal control over
financial reporting.
ITEM 11. EXHIBITS
(a)(1) Registrant's Code of Ethics - Not applicable (please see Item 2).
(a)(2)(i) Treasurer's Section 302 certification.
(a)(2)(ii) President's Section 302 certification.
(b) Combined Section 906 certification.
<Page>
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934 and the
Investment Company Act of 1940, the registrant has duly caused this report to be
signed on its behalf by the undersigned, thereunto duly authorized.
Tax-Managed Mid-Cap Core Portfolio
- ----------------------------------
By: /s/ James B. Hawkes
-------------------
James B. Hawkes
President
Date: December 22, 2004
-----------------
Pursuant to the requirements of the Securities Exchange Act of 1934 and the
Investment Company Act of 1940, this report has been signed below by the
following persons on behalf of the registrant and in the capacities and on the
dates indicated.
By: /s/ Michelle A. Green
---------------------
Michelle A. Green
Treasurer
Date: December 22, 2004
-----------------
By: /s/ James B. Hawkes
-------------------
James B. Hawkes
President
Date: December 22, 2004
-----------------