Form 8802: Requesting a U.S. Residency Certification
Published November 8, 2026
Form 8802 is the application used to request Form 6166, a letter of U.S. residency certification. Foreign payers often ask for this letter before they apply a treaty rate of withholding to income paid to a U.S. resident. The IRS says the letter can also support a value added tax (VAT) exemption request.
This post is general information from the IRS form and its instructions. It does not say whether a particular person is a U.S. resident for tax purposes, and it does not say whether a treaty applies to any payment.
What Form 6166 certifies
Form 6166 certifies that, for the period requested, the applicant was a resident of the United States for federal tax purposes. For a fiscally transparent entity, such as a partnership, the letter certifies that the entity filed an information return and that its partners, owners, or beneficiaries filed as U.S. residents, when required.
The letter does not certify that the applicant is the beneficial owner of an item of income. It also does not certify that a limitation on benefits article is met. A foreign withholding agent may ask for proof of those points directly.
You cannot use Form 6166 to show that U.S. taxes were paid for a foreign tax credit.
Completing the form
Line 4 asks the applicant to check its type, such as an individual, partnership, trust, estate, or corporation. Line 5 asks whether the applicant had to file a U.S. tax return for the periods the certification covers. If the answer is no, line 6 asks about the parent or owner.
Line 7 lists the calendar years requested. Line 8 lists the tax periods the certification will be based on. Line 9 states the purpose, which is income tax or VAT. Line 11 lists the number of certifications needed for each treaty country, using the country codes printed on the form.
If the certification is for the current calendar year, or for a year when no return is due yet, line 10 needs a penalties of perjury statement from the instructions.
Line 3a asks for the address where Form 6166 should be mailed. Line 3b collects information about an appointee, including the appointee's CAF number, if someone will handle the request for you.
Timing
The instructions say to mail the application, with the required payment, at least 45 days before the date you need the letter. The IRS does not process the application until the payment is made. When paying through Pay.gov, the applicant must also upload a copy of Form 8802. The IRS uses the upload only to match the payment to the application.
Early requests have a limit. For a 2026 certification, a request postmarked before December 1, 2025 cannot be processed and is returned to the sender.
Where the letter goes
Once the IRS issues Form 6166, the instructions say to send it to the foreign withholding agent or other appropriate person, unless the IRS directs otherwise. Some foreign countries apply the treaty rate at the time of payment. Others withhold at their statutory rate first and return the excess after proof of U.S. residency is received.
Check the treaty status first
Treaties can change. The instructions list recent partial suspensions and terminations, including Russia, Belarus, and Hungary. Read the current list before you request a letter for a treaty partner.
For the form a foreign person gives a withholding agent to claim a treaty exemption, see Form 8233: Claiming a Tax Treaty Withholding Exemption.
Mistakes to avoid
- Mailing the application without the required payment. Processing does not start until the payment is made.
- Requesting a current-year letter without the penalties of perjury statement.
- Using Form 6166 as proof of a foreign tax credit.
- Assuming the letter proves that a treaty benefit applies. The withholding agent decides what it will accept.
Sources: Sources: IRS, Form 8802, Application for United States Residency Certification (Rev. October 2026) (https://www.irs.gov/pub/irs-pdf/f8802.pdf); Instructions for Form 8802 (Rev. October 2026) (https://www.irs.gov/pub/irs-pdf/i8802.pdf) This is general information, not advice about your specific return.
