How to obtain the document
File Form 8802 (mandatory). Pay the user fee on Pay.gov ('IRS Certs') and enter the confirmation number on page 1; upload a copy of the 8802 to Pay.gov, then mail (IRS, Philadelphia, PA 19255-0625) or fax (877-824-9110 toll-free / 304-707-9792) the signed application. Fees from Oct. 1, 2026: $105 per application for individuals, $230 for non-individuals (previously $85/$185). Submit at least 45 days before the date needed; IRS contacts you after 30 days if delayed. Form 6166 is a letter on U.S. Treasury stationery and can be mailed to a third-party appointee or foreign address listed on the 8802.
Why it goes to the U.S. Department of State
Signed by an IRS official; travel.state.gov names 'IRS certification of U.S. tax residency' as a federal document.
Format the Office of Authentications accepts
Original Form 6166 as issued (Treasury letterhead, IRS official signature, date). Do not notarize.
Filing the request
- Keep the document unaltered
Do not notarize it, write on it or remove staples. Originals or agency-certified copies only.
- Complete Form DS-4194
Name the destination country for each document. Download DS-4194.
- Pay $20 per document
Check or money order payable to ‘U.S. Department of State’ by mail; card at the counter.
- Mail or hand-deliver
Mail: U.S. Department of State, Office of Authentications, 44132 Mercure Cir., PO Box 1206, Sterling, VA 20166-1206. Walk-in: Office of Authentications, 600 19th Street NW, Washington, DC 20006, Drop-off and pick-up 7:30-9:00 a.m., Monday-Thursday, no appointment needed; processing about 7 business days. Max 15…
- Allow for processing
Mail-in: up to 5 weeks from receipt (tracking 'delivered' at the Sterling PO box does not mean processing has started; package takes several days to reach DC). Walk-in: about 7 business days.
Common reasons for rejection
- Photocopy or scan of the 6166 instead of the IRS-issued original.
- Notarized 6166.
Practical notes
- Request multiple originals on one Form 8802 if several countries or years are needed; one fee covers the application.
- VAT-exemption and treaty uses are the IRS's stated purposes; foreign authorities often require the apostille on top.
Non-Hague destinations
For countries outside the Hague Convention the office issues an authentication certificate rather than an apostille, and the document must then be legalized at the destination's embassy or consulate in Washington. See embassy legalization.
Frequently asked questions
Can my state apostille a IRS Form 6166?
No. Only the U.S. Department of State authenticates federal signatures. A state can apostille a notarized copy, but many destinations will not accept that in place of the federal apostille on the original.
How much is the federal apostille fee?
$20 per document, payable to the U.S. Department of State. The fee is charged even if the request is returned unprocessed.
How long does it take?
Mail-in: up to 5 weeks from receipt (tracking 'delivered' at the Sterling PO box does not mean processing has started; package takes several days to reach DC). Walk-in: about 7 business days.
Should I notarize it first?
No. Notarizing a federal document makes it invalid for authentication at the Office of Authentications.
