ACCO Acco Brands Corporation

Notes to Financial Statements

December 31, 2022 and 2021

NOTE 1. Description of the Plan

The following description of the ACCO Brands Corporation 401(k) Plan ("the Plan") is provided for general information purposes only. For a complete description of the Plan, participants should refer to the specific provisions of the Plan document or to the Prospectus/Summary Plan Description, each of which is available from the plan administrator at Four Corporate Drive, Lake Zurich, Illinois 60047.

General: ACCO Brands Corporation ("the Company" or "ACCO") established the Plan as of August 16, 2005, in order to provide for participation by certain employees of ACCO who are paid on a salaried, hourly or commission basis. Generally, all employees of a participating employer are immediately eligible to participate in the Plan.

The Plan is a defined contribution plan. The Plan is subject to the provisions of the Employee Retirement Income Security Act of 1974 ("ERISA"). Fidelity Management Trust Company serves as trustee of the Plan and performs certain recordkeeping and administrative functions for the Plan.

Effective January 1, 2022, the Sidney, New York union participants began to receive Company matching contribution under safe harbor treatment.

Significant features of the Plan are as follows:

Contributions: Each participant may elect to contribute on a pre-tax basis up to 50% of eligible compensation. A participant’s pre-tax contributions may not exceed the dollar amount provided by the Internal Revenue Code ("the Code"), which was $20,500 for 2022.

The Plan also permits each participant to make after-tax contributions, including Roth 401(k) contributions, to the Plan. However, total pre-tax and after-tax contributions generally may not exceed 50% of the participant’s total eligible compensation.

Generally, participants over 50 years of age may elect up to 25% of eligible compensation as either an additional pre-tax catch-up contribution or Roth 401(k) catch-up contribution, which was limited by the Code to $6,500 in 2022.

In addition to the ability to make simultaneous tax deferred and after-tax contributions, the Plan also allows for a participant’s contributions to automatically continue on an after-tax basis once the pre-tax contribution limit has been reached for that year. Participants, who elect to continue contributing to the Plan on an after-tax basis, will contribute at the same pre-tax contribution percentage that was in effect when the limit was reached for that year. In determining the amount of pre-tax and after-tax contributions allowed under the Plan, annual compensation limits are imposed by the Code.

New hires who do not decline enrollment in the Plan within 90 days after first becoming eligible to join the Plan, will be automatically enrolled in the Plan and a pre-tax contribution of 6% will be deducted from the participant’s pay and invested in the T. Rowe Price Retirement fund designed for the participant’s age group.

4

Table of Contents

ACCO BRANDS CORPORATION 401(K) PLAN

Notes to Financial Statements

December 31, 2022 and 2021

The Company contributes on behalf of each eligible participant, an amount equal to 100% of the participant’s contribution up to 6% of eligible compensation. The amount of any Company matching contributions is subject to certain limitations of the Code. In 2010, the Plan became a safe harbor 401(k) plan.

The Plan permits the acceptance of an account balance from another tax-qualified plan or certain individual retirement accounts by means of a direct rollover.

Participant Accounts: Each participant’s account is credited with the participant’s contributions and allocations of the Company’s contributions, is adjusted for allocations of the Plan’s investment income (loss) and administrative expenses and is reduced by the amount of participant withdrawals. Allocations are based on participant earnings or account balances, as defined. The benefit to which a participant is entitled is the benefit that can be provided from the participant’s vested balance.

Investment Elections: Participants direct the investment of their account balance into various investment options offered by the Plan. Except as may be limited by policies concerning excessive short-term trading or blackout periods, each participant can change the investment percentages or transfer all or part of his/her account from one fund to another on a daily basis. The Plan currently offers, in addition to the ACCO Brands Common Stock Fund, a Fully Benefit-Responsive Synthetic Guaranteed Investment Contract (the "SGIC"), and various other collective investment and mutual funds as investment options for participants. Participants can also make investments outside those offered under the Plan and allocate their assets over a potentially wider array of investment options through a self-directed brokerage account. Those investment options include, but are not limited to, common stock, mutual funds, and cash.

Vesting: Participants are always 100% vested in their own contributions as well as any investment earnings on those contributions. Company safe harbor and non-safe harbor matching contributions, as well as any investment earnings on those contributions, are 100% vested immediately.

Notes Receivable from Participants: The current minimum amount a participant can borrow is $1,000 for a principal residence loan and $500 for a general-purpose loan. The maximum amount a participant may borrow is the lesser of (1) an amount which, when added to the highest outstanding balance under the Plan loans during the previous 12 months, does not exceed $50,000, or (2) one-half of the participant's vested account balances.

The term of any loan shall not exceed five years, unless the loan is related to the purchase of the participant’s principal residence. Principal residence loans must be repaid within ten years. Participants can have up to three loans outstanding at any one time, one of which may be a principal residence loan.

Each loan bears a rate of interest equal to the prime rate as reported by Thomson Reuters, as of the last business day of the month prior to the month in which the loan is made. Each loan must be collateralized by a portion of the participant’s account balance and documented by a promissory note payable to the trustee, which is invested in the loan fund. Repayment is made by payroll deductions for so long as the participant is employed by the Company and thereafter by regular installment payments. Loan repayments are invested in accordance with the participant’s investment election in effect at the time of repayment. A one-time loan setup fee of $50 is paid by the participant and is deducted from the participant’s account at the time the loan is processed.

(Continued)

5

Table of Contents

ACCO BRANDS CORPORATION 401(K) PLAN

Notes to Financial Statements

December 31, 2022 and 2021

Distributions and Withdrawals: Benefits are payable from a participant’s account under the Plan’s provisions, upon a participant’s death, retirement or other termination of employment in a lump sum or in installment payments. The Plan also permits withdrawals to be made by participants who have incurred a "hardship" as defined in the Plan or after the attainment of age 59½.

Administrative Expenses: Investment management expenses incurred by the Plan are netted against earnings prior to allocation to participant accounts. Transaction charges (for loan and certain benefit payment transactions), short-term trading fees and certain record-keeper fees are paid by the Plan by reducing the balances of those participants initiating the transactions. Fees incurred in the administration of the Plan, such as audit fees, legal fees and investment advisory fees, have been paid by the Plan.

Plan Termination: Although it has expressed no intent to do so, the Company has the right under the Plan to discontinue its contributions at any time and the Board of Directors of the Company may terminate the Plan at any time subject to the provisions of ERISA and its related regulations.

NOTE 2. Summary of Significant Accounting Policies

Basis of Accounting: The accompanying financial statements of the Plan have been prepared on the accrual basis of accounting.

Investment Valuation and Income Recognition: The Plan’s investments are stated at fair value (see Note 3), other than the SGIC, which is presented at contract value (see Note 6).

Contract value represents contributions made to the contract, plus earnings, less participant withdrawals and administrative expenses. Participants in fully benefit-responsive contracts may ordinarily direct the withdrawal or transfer of all or a portion of their investment at contract value. The Plan holds a direct interest in such contracts through its investment in the SGIC.

Dividend income is recorded on the ex-dividend date. Interest income is recorded on an accrual basis. Purchases and sales of securities are recorded on a trade-date basis. Net appreciation (depreciation) includes the Plan’s gains and losses on investments bought and sold as well as held during the year.

Use of Estimates: The preparation of financial statements in conformity with U.S. generally accepted accounting principles requires the Plan’s management to make estimates and assumptions that affect certain amounts reported in the financial statements and disclosures, and actual results could differ from those estimates.

Risks and Uncertainties: The Plan invests in mutual funds, collective investment funds, the SGIC, and Company common stock. Investment options for the self-directed brokerage accounts include, but are not limited to, common stock, mutual funds, and cash. These investments are exposed to various risks, such as interest rate, liquidity, market, and credit risks. Due to the level of risk associated with certain investments and the sensitivity of certain fair value estimates to changes in valuation assumptions, it is at least reasonably possible that changes in the values of investments will occur in the near term and that such changes could materially affect the amounts reported in the Statement of Net Assets Available for Benefits and participants’ individual account balances.

(Continued)

6

Table of Contents

ACCO BRANDS CORPORATION 401(K) PLAN

Notes to Financial Statements

December 31, 2022 and 2021

Payments of Benefits: Benefits are recorded when paid.

Notes Receivable from Participants: Notes receivable from participants are reported at their unpaid principal balance plus any accrued but unpaid interest, with no allowance for credit losses, as repayments of principal and interest are generally received through payroll deductions and the notes are collateralized by the participants’ account balances.

NOTE 3. Investment Valuation Measurements

Fair value is the price that would be received by the Plan for an asset or paid by the Plan to transfer a liability (an exit price) in an orderly transaction between market participants on the measurement date in the Plan’s principal or most advantageous market for the asset or liability. Fair value measurements are determined by maximizing the use of observable inputs and minimizing the use of unobservable inputs when measuring fair value. The hierarchy places the highest priority on unadjusted quoted market prices in active markets for identical assets or liabilities (level 1 measurements) and gives the lowest priority to unobservable inputs (level 3 measurements). The three levels of inputs within the fair value hierarchy are defined as follows:

Level 1: Quoted prices (unadjusted) of identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date.

Level 2: Significant other observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data.

Level 3: Significant unobservable inputs that reflect a reporting entity’s own assumptions about the assumptions that market participants would use in pricing an asset or liability.

In some cases, a valuation technique used to measure fair value may include inputs from multiple levels of the fair value hierarchy. The lowest level of significant input determines the placement of the entire fair value measurement in the hierarchy.

The following descriptions of the valuation methods and assumptions used by the Plan to estimate the fair value of investments apply to investments held directly by the Plan.

Mutual funds and common stock: The fair values of mutual funds and common stock investments are determined by obtaining quoted prices on nationally recognized securities exchanges (level 1 inputs).

Self-directed brokerage accounts: These accounts provide the opportunity to invest in a broad range of investment options including, but not limited to, common stock, mutual funds, and cash. The fair values of investments in common stock and mutual funds are determined by obtaining quoted prices on nationally recognized securities exchanges (level 1 inputs).

(Continued)

7

Table of Contents

ACCO BRANDS CORPORATION 401(K) PLAN

Notes to Financial Statements

December 31, 2022 and 2021

Collective investment funds: The fair values of the Plan’s interest in the collective investment funds (the "CIFs") are based upon the net asset value ("NAV") of investments at fair value. The per unit NAV of the CIFs is calculated at the end of each day that the New York Stock Exchange is open as of the close of regular trading. Contributions to and withdrawals from the CIFs are based on the NAV per unit as calculated at the end of each day.

Participant-directed withdrawals may be made at any time without penalty, regardless of their frequency or amount, however participant-directed withdrawals may not be transferred to a competing fund for 90 days after withdrawal. A competing fund is an investment option available under the Plan that is primarily comprised of high-quality fixed income securities with an average duration of less than or equal to 3.5 years.

The methods described above may produce a fair value calculation that may not be indicative of net realizable value or reflective of future fair values. Furthermore, while the Plan believes its valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date.

The following tables set forth by level, within the fair value hierarchy, the Plan’s assets as of December 31, 2022 and 2021 that are measured at fair value on a recurring basis:

NOTE 4. Tax Status

The Internal Revenue Service (the "IRS") has determined and informed the Company by letter dated September 26, 2013 that the Plan is designed in accordance with applicable sections of the Internal Revenue Code (the "Code").

(Continued)

8

Table of Contents

ACCO BRANDS CORPORATION 401(K) PLAN

Notes to Financial Statements

December 31, 2022 and 2021

Although the Plan has been amended since receiving the determination letter, Plan management believes that the Plan is designed and being operated in compliance with the applicable requirements of the Code. Therefore, no provision for income taxes has been included in the Plan’s financial statements.

Accounting principles generally accepted in the U. S. require plan management to evaluate tax positions taken by the Plan and recognize a tax liability if the Plan has taken an uncertain position that more likely than not would not be sustained upon examination by the Department of Labor or the IRS. The plan administrator has analyzed the tax positions taken by the Plan, and has concluded that as of December 31, 2022 and 2021, there are no uncertain positions taken or expected to be taken that would require recognition of a liability (or asset) or disclosure in the financial statements. The Plan is subject to routine audits by taxing jurisdictions; however, there are currently no audits for any tax periods in progress. The plan administrator believes it is no longer subject to income tax examinations for years prior to 2019.

NOTE 5. Party-in-Interest Transactions

Parties-in-interest are defined under Department of Labor regulations as any fiduciary of the Plan, any party rendering service to the Plan, the employer and certain others. The Company pays certain fees for the administration of the Plan.

Certain Plan investments are shares of registered investment companies (mutual funds) managed by Fidelity Investments, an affiliate of Fidelity Management Trust Company. Fidelity Management Trust Company is the trustee as defined by the Plan. Accordingly, these investments qualify as party-in-interest investments. Professional fees and administrative fees paid by the Plan in 2022 also qualify as party-in-interest transactions. The investment in ACCO Brands Corporation common stock ("ACCO stock") is also a party-in-interest investment. As of December 31, 2022 and 2021, the value of the ACCO stock held by the Plan within the ACCO Brands Common Stock Fund was $2,285,964 and $2,935,783, respectively, and the number of shares held was 408,938 and 355,239, respectively.

Participants in the Plan are permitted to borrow funds from their vested balance as described in "Note 1. Description of the Plan." These transactions qualify as party-in-interest transactions. Actual fees paid by the Plan for investment advisory and consulting services, also qualify as party-in-interest transactions and are included in administrative expenses in the accompanying financial statements.

NOTE 6. Fully Benefit-Responsive Synthetic Guaranteed Investment Contract

The Plan holds a SGIC, which consists of units of participation in the Prudential Core Intermediate Bond Fund (a collective trust fund, the "Collective Trust") managed by Prudential Trust Company and a wrapper contract issued by Prudential Insurance Company of America (the "Wrapper").

Participants may ordinarily direct the withdrawal or transfer of all or a portion of their investments from the SGIC at contract value due to the contract value guarantee provided to the Plan under the Wrapper. There are no reserves against the contract value for credit risk of the issuer or otherwise.

There are no events that limit the ability of the Plan to transact at contract value as long as the contract remains in force. The investment contract does specify events, which may result in a termination. Such events include Plan

(Continued)

9

Table of Contents

ACCO BRANDS CORPORATION 401(K) PLAN

Notes to Financial Statements

December 31, 2022 and 2021

termination or merger, early retirement incentive, layoffs, etc. Termination of the contract would cause distributions to be payable at fair value. In addition, Prudential may not cause the contract to be terminated at an amount other than contract value. Currently, management believes that the occurrence of an event that would cause the Plan to transact contract distributions at less than contract value is not probable.

The crediting interest rate of the contract is based upon an agreed-upon formula with the issuer, as defined in the contract agreement, but cannot be less than zero. The interest rates are reviewed on a semi-annual basis for resetting per the contract. The key factors that influence future interest crediting rates could include the following: the level of market interest rates; the amount and timing of participant contributions; transfers and withdrawals into/out of the contracts; and the duration of the underlying investments backing the contracts.

The fair value of the Wrapper is based upon a comparison of the cost of the Wrapper and current re-bid prices for a similar wrapper contract as of the financial statement date (level 3 inputs). The value of the Wrapper was determined to be zero as of December 31, 2022 and 2021.

(Continued)

10

Table of Contents

NOTE 8. Subsequent Events

Plan management has evaluated subsequent events for recognition and disclosure through June 19, 2023, and has determined that no significant events occurred after December 31, 2022, but prior to the issuance of these financial statements, that would have a material impact on its financial statements.

11

Table of Contents

SUPPLEMENTAL SCHEDULE

12

Table of Contents