Basis of Presentation and Summary of Significant Accounting Policies | Basis of Presentation and Summary of Significant Accounting Policies Basis of Presentation and Principles of Consolidation The accompanying consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States, which is referred to as U.S. GAAP, and include the accounts of Upwork Inc. and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. In 2023, the Company changed the name of its Upwork Enterprise offering to Enterprise Solutions. Concurrently, to align with customer needs and internal decision-making, the Company combined Enterprise Solutions and Managed Services into a suite of Enterprise offerings. In order to conform to the current period presentation as of December 31, 2023, the Company presents revenue from Enterprise Solutions and Managed Services together as Enterprise revenue in prior periods and no longer reports revenue from its Enterprise Solutions offering in Marketplace revenue. Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make certain estimates, judgments, and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the periods presented. Such estimates include, but are not limited to: the useful lives of assets; assessment of the recoverability of long-lived assets; goodwill impairment; standalone selling price of material rights and the period of time over which to defer and recognize the consideration allocated to the material rights; allowance for expected credit losses; liabilities relating to transaction losses; stock-based compensation; and accounting for income taxes. Management bases its estimates on historical experience and on various other assumptions that management believes to be reasonable under the circumstances. The Company evaluates its estimates, assumptions, and judgments on an ongoing basis using historical experience and other factors and revises them when facts and circumstances dictate. The Company is not aware of any specific event or circumstance that would require an update to its estimates or judgments or a revision of the carrying value of its assets or liabilities. These estimates may change as new events occur and additional information is obtained. Actual results could differ materially from these estimates under different assumptions or conditions. Cash and Cash Equivalents The Company classifies as cash and cash equivalents its cash held in checking and interest-bearing accounts and investments in money market funds, U.S. government securities, and debt securities with maturities of 90 days or less from the date of purchase. Restricted Cash As of December 31, 2023 and 2022, the Company maintained restricted cash of $4.4 million related to cash reserve requirements under the escrow laws and regulations of the California Department of Financial Protection and Innovation and collateral for letters of credit issued in conjunction with operating leases. Short-term restricted cash included in prepaid expenses and other current assets was $3.6 million as of December 31, 2023 and 2022, and long-term restricted cash included in other assets, noncurrent was $0.8 million as of December 31, 2023 and 2022. Funds Held in Escrow, Including Funds in Transit The Company maintains its customers’ funds held in escrow in demand or interest-bearing checking accounts at U.S. financial institutions, as well as two California licensed money transmitters. The balance in these accounts was in excess of federally insured limits as of December 31, 2023 and 2022. Customers’ funds held in escrow are denominated exclusively in U.S. dollars. The Company is an internet escrow agent and is therefore required to hold its customers’ escrowed funds and escrow funds in transit in trust as an asset and record a corresponding liability for escrow funds payable on its consolidated balance sheets. For this reason, funds held in escrow, including funds in transit, are restricted cash. Escrow funds in transit arise due to the time it takes to clear transactions through external payment networks. When clients fund their escrow account using credit cards, there is a clearing period before the cash is received and settled. Accordingly, the funds are treated as escrow funds in transit until the transaction is settled to the escrow trust bank account or, in the case of international credit card settlements, to the Company’s bank accounts. Escrow regulations require the Company to fund the trust with its own operating cash if there is ever a shortage due to the timing of cash receipts from clients for completed hourly billings. As of December 31, 2023 and 2022, the Company recorded $212.4 million and $161.5 million, respectively, as funds held in escrow, including funds in transit. The below table reconciles cash, cash equivalents, and restricted cash as reported in the consolidated balance sheets to the total of the same amounts shown in the consolidated statements of cash flows for the years ended December 31, 2023, 2022, and 2021: (In thousands) 2023 2022 2021 Cash and cash equivalents $ 79,641 $ 129,384 $ 187,205 Restricted cash 4,390 4,390 4,040 Funds held in escrow, including funds in transit 212,387 161,457 160,813 Total cash, cash equivalents, and restricted cash as shown in the consolidated statement of cash flows $ 296,418 $ 295,231 $ 352,058 Marketable Securities The Company’s marketable securities consist of money market funds, commercial paper, treasury bills, corporate bonds, U.S. government securities, asset-backed securities, and other types of fixed income securities issued by foreign governments or entities and denominated in U.S. dollars, which have contractual maturities within 36 months from the date of purchase. The marketable securities are available for current operations and are classified as available-for-sale. These marketable securities are carried at estimated fair value with unrealized gains and losses, net of taxes, included within the stockholders’ equity section of the Company’s consolidated balance sheet. The Company periodically assesses its portfolio of debt investments for impairment. For debt securities in an unrealized loss position, this assessment first takes into account the Company’s intent to sell, or whether it is more likely than not that the Company will be required to sell the security before recovery of its amortized cost basis. If either of these criteria are met, the debt security’s amortized cost basis is written down to fair value through other income (expense), net. For debt securities in an unrealized loss position that do not meet the aforementioned criteria, the Company assesses whether the decline in fair value below the amortized cost basis resulted from a credit loss or other factors. In making this assessment, the Company considers factors such as the extent to which fair value is less than the amortized cost basis, the financial condition of the issuer, any changes to the rating of the security by a rating agency, and any adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss may exist, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses will be recorded through other income (expense), net, limited by the amount that the fair value is less than the amortized cost basis. Any additional impairment not recorded through an allowance for credit losses is recognized in other comprehensive income (loss). Changes in the allowance for credit losses are reflected as provision for (or reversal of) credit loss expense. Losses are charged against the allowance when management believes the uncollectability of an available-for-sale security is confirmed or when either of the criteria regarding intent or requirement to sell are met. These changes are recorded in other income (expense), net. The Company determines realized gains or losses from the sale of marketable securities on a specific identification method and records such gains or losses in other income (expense), net within the Company’s consolidated statements of operations and comprehensive income (loss). Escrow Funds Payable Escrow funds payable represent customer funds that are held in escrow by the Company on behalf of both talent and clients. Escrow funds payable to talent are comprised primarily of funds available to be withdrawn by talent for work performed and paid by clients. Escrow funds payable to clients primarily represent deposits received from certain clients to set up an account or to apply toward future payments to talent upon completion of the project defined and agreed between the client and talent. Concentration of Risk Financial instruments that subject the Company to concentration of risk consist primarily of cash, restricted cash, funds held in escrow, including funds in transit, and trade and client receivables. The Company maintains its cash balances with large, high-credit quality financial institutions and other payment companies. At times, such deposits may be in excess of federally insured limits. The Company has not experienced any losses on its deposits. Credit risk on trade receivables is limited as a result of the large size of the Company’s client base as well as a large portion of payments made using pre-authorized credit cards. The Company performs ongoing credit evaluations of its clients and maintains allowances for potential credit losses. For any receivables that are deemed not collectible, losses are recorded when probable and estimable. These losses, when incurred, have been within the range of the Company’s expectations. The Company did not have any clients that accounted for more than 10% of trade and client receivables as of December 31, 2023. One client accounted for more than 10% of trade and client receivables as of December 31, 2022. For the years ended December 31, 2023, 2022 and 2021, the Company did not have any clients that accounted for more than 10% of total revenue. The Company is dependent upon third parties, such as Amazon Web Services, in order to meet the uptime and performance needs of its customers. Fair Value of Financial Instruments The Company’s financial instruments consist of cash and cash equivalents, restricted cash, funds held in escrow, including funds in transit, marketable securities, trade and client receivables, prepaid and other current assets, escrow funds payable, and debt. The Company believes that the carrying values of financial instruments approximate their fair values. Trade and Client Receivables and Related Allowance for Expected Credit Losses Trade and client receivables are primarily comprised of amounts receivable from clients for completed work, including amounts in transit. It also includes unbilled amounts due from clients primarily through the Company’s Managed Services offering. Trade and client receivables are recorded and stated at realizable value, net of an allowance for expected credit losses. Credit is extended generally without collateral to the Company’s clients of its Enterprise offerings based on an initial and ongoing evaluation of their financial condition and other factors. In aggregate, gross trade receivables were $24.8 million and $22.6 million and gross client receivables were $83.4 million and $54.7 million as of December 31, 2023 and 2022, respectively. The allowance for expected credit losses is the Company’s estimate of the probable credit losses on accounts receivable. The Company periodically assesses the collectability of the accounts and determines the allowance recognized by taking into consideration the aging of its receivable balances, historical write-off experience, probability of collection, and other relevant data. Trade and client receivables are written off against the allowance when management determines a balance is uncollectible and no longer actively pursues collection of the receivable. The following table presents the changes in the allowance for expected credit losses as of December 31, 2023, 2022, and 2021: (In thousands) 2023 2022 2021 Allowance for expected credit losses, beginning balance $ 12,464 $ 3,410 $ 1,661 Provision for expected credit losses 9,490 22,167 4,803 Amounts written off (16,813) (13,113) (3,054) Allowance for expected credit losses, ending balance $ 5,141 $ 12,464 $ 3,410 Derivative Instruments The Company uses derivative financial instruments not designated as hedges, such as foreign currency forward contracts, to minimize the short-term impact of foreign currency exchange rate fluctuations on certain foreign currency denominated assets and liabilities, as well as certain foreign currency denominated expenses, hedging the gains or losses generated by the re-measurement of significant foreign currency denominated monetary assets and liabilities. The Company does not enter into derivative instruments for speculative or trading purposes and these instruments generally have maturities within 12 months. The foreign currency forward contracts are recorded at fair value and, when in gain positions, are reported within prepaid expenses and other current assets. When in loss positions, the foreign currency forward contracts are recorded within accrued expenses and other current liabilities in the consolidated balance sheets. Gains or losses from changes in the fair value of these foreign currency forward contracts not designated as hedging instruments are recorded in other income (expense), net to offset the changes in the fair value of the underlying assets or liabilities being hedged. The notional amounts associated with the Company’s foreign currency forward contracts as of December 31, 2023 and 2022 were $7.0 million and $7.2 million, respectively, none of which were designated as cash flow hedges. The carrying values of the foreign currency forward contracts approximated their fair values due to their relatively short settlement durations. The fair values of the Company’s outstanding foreign currency forward contracts not designated as hedging instruments as of December 31, 2023 and 2022 were not material. Gains on foreign currency forward contracts not designated as hedging instruments were $0.5 million for the year ended December 31, 2023. Losses on foreign currency forward contracts not designated as hedging instruments were $0.2 million for the year ended December 31, 2022. Losses on foreign currency forward contracts not designated as hedging instruments were $0.5 million for the year ended December 31, 2021. Leases The Company accounts for leases in accordance with Financial Accounting Standards Board, which is referred to as the FASB, Accounting Standards Update, which is referred to as ASU, No. 2016-02, Leases (Topic 842), which the Company adopted on December 31, 2019 effective as of January 1, 2019 using the effective date method. Property and Equipment, Net Property and equipment are stated at cost, net of accumulated depreciation and amortization. Depreciation is calculated using the straight-line method over the estimated useful lives of the related assets, which are generally two to five years. Leasehold improvements are amortized on a straight-line basis over the shorter of the remaining lease term or their estimated useful lives. Repair and maintenance costs are charged to expense as incurred. Internal-Use Software and Platform Development Costs The Company’s policy is to capitalize certain costs to develop its internal-use software and platform when (i) preliminary project planning is completed, (ii) the Company has committed project resourcing, and (iii) it is probable that the project will be completed and the software will be used as intended. Costs incurred for enhancements that are expected to result in additional significant functionality are also capitalized. Such costs are generally amortized on a straight-line basis over their estimated useful lives determined on a project-by-project basis, which historically has ranged between two Segment Information The Company has one reportable segment. The Company’s chief operating decision maker is its President and Chief Executive Officer, who reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. Goodwill, Acquired Intangible and Other Long-Lived Assets Goodwill represents the excess of the aggregate fair value of the consideration transferred over the fair value of the net tangible and identifiable intangible assets acquired in a 2014 business combination. Goodwill is not amortized, but rather is assessed for impairment at least annually, or more frequently if events and changes in circumstances indicate that its carrying amount may not be recoverable. The Company performs its annual impairment assessment during the fourth quarter of each calendar year based on a single reporting unit structure by comparing the carrying value of the reporting unit to its fair value. An impairment would occur if the carrying amount of a reporting unit exceeded the fair value of that reporting unit. For 2023, the Company conducted its goodwill impairment testing by performing step one of the quantitative assessment, of the two-step impairment model. The fair value was determined by the Company using quoted market prices of the Company’s common stock. The Company determined that the fair value of its reporting unit exceeded the carrying value, and, as such, the Company concluded that there was no impairment of goodwill at the impairment testing date. There has been no impairment of goodwill for any of the periods presented. The Company’s intangible assets consist of an identifiable, finite-lived intangible asset, namely an assembled workforce, acquired as part of an asset acquisition in November 2023. The assembled workforce intangible asset is carried at cost, less accumulated amortization. The Company amortizes the assembled workforce intangible asset over its estimated useful life of two years, based on the pattern in which the economic benefits of the intangible asset is consumed, or the straight-line method when the pattern cannot be reliably determined. Amortization expense is included in research and development expense on the Company’s consolidated statement of operations and comprehensive income (loss). The Company periodically reviews the remaining estimated useful lives of its long-lived tangible and amortizable intangible assets. If the estimated useful life assumption for any asset is changed, the remaining unamortized balance would be depreciated or amortized over the revised estimated useful life, on a prospective basis. Intangible amortization expense related to an assembled workforce is included in research and development expense in the Company’s statement of operations. The Company’s long-lived assets consist of property and equipment and internal-use software and platform development costs. The Company evaluates the recoverability of its long-lived assets, including identifiable intangible assets, for possible impairment whenever events or circumstances indicate that the carrying amount of such assets may not be recoverable. Recoverability of these assets is measured by comparing the carrying amounts to the future undiscounted cash flows the assets are expected to generate. If it is determined that the asset group is not recoverable, an impairment loss is recorded in the amount by which the carrying amount of the asset group exceeds the aggregate future undiscounted cash flows. When an impairment loss is recognized, the carrying amount of such assets is reduced to fair value. Convertible Senior Notes The Company accounts for the 0.25% convertible senior notes due 2026, which are referred to as the Notes, as a single liability measured at amortized cost. The carrying value of the liability equals the proceeds received from the issuance of the Notes less debt issuance costs. In March 2023, the Company entered into separate, privately negotiated repurchase agreements with a limited number of institutional holders of the Notes to repurchase for cash an aggregate of $214.0 million principal amount of the Notes for an aggregate cash payment of $170.8 million, which are collectively referred to as the Note Repurchases. See “Note 7—Debt” for additional information. Debt Issuance Costs Debt issuance costs incurred in connection with securing the Company’s financing arrangements are capitalized and amortized over the term of the respective financing arrangement under the straight-line method as the results obtained are not materially different from those that would result from the use of the effective interest method. Debt issuance costs are generally presented in the Company’s consolidated balance sheets as a reduction to the carrying amount of the outstanding borrowings. Revenue Recognition In 2023, the Company changed the name of its Upwork Enterprise offering to Enterprise Solutions. Concurrently, to align with customer needs and internal decision-making, the Company combined Enterprise Solutions and Managed Services into a suite of Enterprise offerings. In order to conform to the current period presentation as of December 31, 2023, the Company presents revenue from Enterprise Solutions and Managed Services together as Enterprise revenue in prior periods and no longer reports revenue from its Enterprise Solutions offering in Marketplace revenue. The Company generates revenue from clients and talent from its Marketplace and Enterprise offerings. The Company accounts for revenue in accordance with FASB ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which the Company adopted on December 31, 2019 effective as of January 1, 2019 using the modified retrospective method. Revenue is recognized upon transfer of control of promised services to customers in an amount that reflects the consideration the Company expects to receive in exchange for those services. In the ordinary course of business, the Company makes payments to customers when those customers provide services in their capacity as vendors. These payments are for distinct services and are at fair value. These transactions are primarily with certain financial institutions that the Company uses as payment processors on the work marketplace. The Company accounts for the consideration payable to these customers in their capacity as vendors as a purchase of services from a vendor and records such payments in either cost of revenue or sales and marketing within the consolidated statements of operations and comprehensive income (loss). Marketplace Offerings The Company’s Marketplace revenue represents the majority of its revenue and is derived from its Marketplace offerings, which include all offerings other than the Enterprise offerings—Enterprise Solutions, previously referred to as Upwork Enterprise, and Managed Services. The Company generates Marketplace revenue from both talent and clients. Marketplace revenue is primarily generated from talent service fees, and to a lesser extent, client marketplace fees. The Company also generates Marketplace revenue from fees for premium offerings, such as its Upwork Payroll offering, as well as purchases of Connects, talent memberships, and other services, such as foreign currency exchange when clients choose to pay in currencies other than the U.S. dollar. The Company earns fees from talent under its Marketplace offerings and associated premium offerings, which represent a single promise to provide continuous access (i.e., stand-ready performance obligation) to the Company’s work marketplace and site services. As each day of providing access to the work marketplace and site services (including, but not limited to, communication, invoicing, reporting, dispute resolution, and payment services) is substantially the same and talent simultaneously receive and consume the benefits as access is provided, the Company’s single promise is comprised of a series of distinct service periods. The Company allocates consideration to each distinct service period in which it has the contractual right to bill. The Company’s talent arrangements may include fixed and variable consideration, or a combination of the two, comprised of the following: Service fees. Talent are provided access to the Company’s work marketplace to market their businesses, send proposals to and communicate with prospective clients, and, if engaged by a client, to perform specified services agreed between talent and clients, which are referred to as talent services. Talent charge clients on an hourly or a milestone basis for services rendered to clients through the Company’s work marketplace, which are referred to as talent billings. Prior to May 2023, the Company charged talent a service fee as a percentage of talent billings primarily using a tiered service fee model based on cumulative lifetime billings by talent to each client. In May 2023, the Company retired the tiered service fee structure for talent working with clients on its Marketplace offering— ranging from 5% to 20%—in favor of a simplified flat service fee of 10%. This change took effect on new contracts and existing contracts that would have otherwise been subject to a 20% fee under the tiered service fee model. Talent that had existing contracts with a 5% fee under the tiered service fee model retained that rate for those contracts through the end of 2023. Prior to this change, talent service fee arrangements subject to tiered service fees also included contract renewal options that represented a material right. The Company takes no responsibility for talent services, and therefore, does not control talent services. Additionally, talent and clients negotiate and agree upon the scope and the price for talent services directly with each other, and the Company is not a party to those agreements. Accordingly, for these arrangements, the Company presents revenue on a net basis, as an agent. The Company recognizes the service fees for each distinct service period when it has the contractual right to bill for the services. Withdrawal fees . The Company charges withdrawal fees to talent when talent withdraw their escrow funds held by the Company. A withdrawal fee is charged for each withdrawal transaction, which represents variable consideration. The Company presents revenue from withdrawal fees on a gross basis as a principal and not net of the third-party payment processing costs incurred because the Company controls the payment processing services prior to providing to the Company’s talent. The Company recognizes the withdrawal fees when transactions are processed, which is when it has the contractual right to bill for the services. Membership fees. The Company charges membership fees to talent. These fees are fixed consideration and are charged monthly. The Company recognizes the revenue over the period of the membership, which is generally monthly, consistent with the common measure of progress for the entire performance obligation. The Company charges fees to talent for the purchase of Connects, which are virtual tokens required for talent to bid on projects on the Company’s work marketplace. Connects represent a separate performance obligation. Connects fees represent fixed consideration and are allocated to and recognized in the distinct service period in which the Connects are used by talent. Certain of the Company’s contracts with talent contain multiple performance obligations in the event the Company determines a material right exists. Specifically, prior to the shift to a simplified flat service fee in May 2023, the arrangements with talent subject to tiered service fees included contract renewal options that represent a material right. For such arrangements, the Company allocated revenue to each performance obligation based on its relative standalone selling price by applying the portfolio approach practical expedient under Topic 606. Standalone selling prices for offerings subject to tiered service fees were estimated based on observable transactions when these services were sold on a standalone basis. Standalone selling price for a material right was estimated by determining the discount that talent would obtain when exercising the option, adjusted for the likelihood that the option will be exercised. Significant judgment was applied in the application of the portfolio approach practical expedient, which included estimating the standalone selling price of the material rights and the period of time over which to defer and recognize the consideration allocated to the material rights. Specifically, management applied significant judgment in assessing the appropriateness of the model for the estimates, which included assessing the appropriateness of the methodology and relevant data inputs to (i) estimate the standalone selling price of the material rights, which included the standalone selling price of the services when sold separately and the likelihood of exercise of the material rights; and (ii) estimate the period of time over which to defer and recognize the consideration allocated to the material rights. The Company utilized historical customer transaction data in developing the estimates. The Company recognized revenue related to the material rights based on the Company’s estimate of when the material rights were exercised and adjusted revenue for changes in estimates in the period of change on a cumulative catch-up basis. The Company earns fees from clients under the Marketplace offerings, which represents a single promise to provide continuous access (i.e., stand-ready performance obligation) to the Company’s work marketplace and site services. As each day of providing access to the work marketplace and site services is substantially the same and the client simultaneously receives and consumes the benefits as access is provided, the Company’s single promise under its Marketplace offering is comprised of a series of distinct service periods. The Company’s Marketplace offerings may include fixed and variable consideration, or a combination of the two, comprised of the following: Client marketplace fees. The Company charges a client marketplace fee on a per-transaction basis and is considered variable consideration. Client marketplace fees are assessed on both fixed price and hourly contracts. The Company allocates client marketplace fees to each distinct service period based on the contractual right to bill. For fixed price contracts, the Company recognizes revenue when a client funds a contract, and for hourly contracts, the Company recognizes revenue at the end of the weekly billing period, which is when the Company has the contractual right to bill for the services. For client marketplace fees, the Company presents revenue on a gross basis as a principal and not net of the third-party payment processing costs incurred because the Company controls the services prior to providing to the Company’s clients. Contract initiation fees. In April 2023, the Company introduced a contract initiation fee for clients on the Marketplace offering. The Company charges a contract initiation fee on new contracts between clients and talent, which is considered fixed consideration. The contract initiation fee is assessed on both fixed price and hourly contracts. The Company allocates the contract initiation fee to each distinct service period based on the contractual right to bill. For fixed price contracts, the Company recognizes revenue when a client initially funds a contract, and for hourly contracts, the Company recognizes revenue at the first weekly billing period, which is when the Company has the contractual right to bill for the services. For contract initiation fees, the Company presents revenue on a gross basis as a principal and not net of the third-party payment processing costs incurred because the Company controls the services prior to providing to the Company’s clients. Foreign currency exchange fees. The Company charges clients a fixed mark-up above foreign currency exchange rates that are charged to the Company when the Company collects amounts denominated in foreign currency. Foreign currency exchange fees are variable consideratio |