Company: COST
Filing Date: 2025-06-27
Form Type: 11-K
Source: 0000909832-25-000038
Chunk: 11

Company: COSTCO WHOLESALE CORP /NEW
Filing Date: 2025-06-27
Form: 11-K
Chunk 11
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 right under the Plan to discontinue its contributions at any time and to terminate the Plan, subject to ERISA and the requirements of the collective bargaining agreements with the Teamsters. In the event of termination, participants remain 100% vested in their accounts.

(6)

#### Tax Status
In a determination letter dated June 9, 2017, the Internal Revenue Service informed the Company that the Plan is designed in accordance with applicable sections of the IRC. The Plan has since been restated and amended. The Plan Administrator believes that the Plan is designed and is being operated in compliance with the IRC.

<div align='center'>8</div>

#### COSTCO 401(k) RETIREMENT PLAN
<div align='center'>Notes to Financial Statements (Continued)

December 31, 2024 and 2023</div>

U.S. GAAP requires the Plan Administrator to evaluate tax positions taken by the Plan and recognize a tax liability (or asset) if the Plan has taken an uncertain position that more likely than not would not be sustained upon examination by the IRS. The Plan Administrator has concluded that as of December 31, 2024, 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; there are currently no audits in progress.

(7)

#### Party-in-Interest and Related Party Transactions
Certain Plan investments are in funds, trusts, and accounts managed by Northern Trust Company, the trustee for the Plan, and by T. Rowe Price Trust Company or T. Rowe Price Associates, Inc., which are affiliates of the recordkeeper for the Plan, T. Rowe Price Retirement Services, Inc. These entities are considered "parties-in-interest" as such term is defined in the ERISA.

As the Plan sponsor, the Company is a party-in-interest with respect to the Plan. At December 31, 2024 and 2023, the Plan held 22,926,000 and 24,205,000 shares of Costco common stock. During 2024, 1,192,000 shares were purchased and 2,471,000 shares were sold.

<div align='center'>9</div>

#### COSTCO 401(k) RETIREMENT PLAN
<div align='center'>Schedule H, Line 4i - Schedule of Assets (Held at End of Year)

EIN: 91-1223280 Plan #: 002