ESS Tech, Inc.

Our independent registered public accounting firm is KPMG LLP; Portland, Oregon; Auditor Firm ID:185.

Fees Paid to the Independent Registered Public Accounting Firm

The following table presents fees for professional audit services and other services rendered to us by EY LLP and KPMG LLP for our fiscal years ended December 31, 2024 and 2023.

(1)“Audit Fees” consist of fees billed for professional services rendered in connection with the audit of our consolidated financial statements, reviews of our quarterly consolidated financial statements and related accounting consultations and services that are normally provided by the independent registered public accountants in connection with statutory and regulatory filings or engagements for those fiscal years. This category also includes

• 100 - fees for services incurred in connection with our registration statements on Form S-1, Form S-3 and Form S-8 including comfort letters and consents.

(2)“Tax Fees” consists of tax return preparation and other tax matters.

Auditor Independence

In 2024, there were no other professional services provided by KPMG, other than those listed above, that would have required our audit committee to consider their compatibility with maintaining the independence of KPMG.

Pre-Approval of Audit and Permissible Non-Audit Services of Independent Registered Public Accounting Firm

Our audit committee has established a policy governing our use of the services of our independent registered public accounting firm. Under this policy, our audit committee is required to pre-approve all services performed by our independent registered public accounting firm in order to ensure that the provision of such services does not impair such accounting firm’s independence. All services provided by EY and KPMG for our fiscal years ended December 31, 2024 and 2023 were pre-approved by our audit committee.

• 101 -

Part IV