Listed as a CPA in IRS public preparer records. Source: IRS PTIN FOIA extract (Feb 2026), retrieved October 23, 2026. https://www.irs.gov/pub/foia/foia-illinois-extract.csv No state license number is on file. Specialties are blank until this preparer claims the listing. CPA Seek does not contact preparers.

Gregory O'Brien

CPA · Deloitte Tax LLP

Chicago, Illinois 60606

Gregory O'Brien, CPA in Chicago, IL

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Gregory O'Brien, CPA in Chicago · CPA Seek