Apostille Services for U.S. IRS Documents – 6166, EIN, 147C, 1065

If you're conducting business internationally or handling tax matters abroad, you may be asked to provide official IRS documents. In many cases, these documents must be legalized with an apostille to be accepted outside the United States.
This guide explains which IRS documents can be apostilled, which cannot — and why — along with clear alternatives if your document isn't eligible.

What Is an Apostille for IRS Documents?
An apostille is an international certificate that verifies the authenticity of a U.S. federal document for legal use abroad in over 100 countries under the Hague Convention.
IRS-related apostilles are often required to:

• Confirm U.S. tax residency
• Comply with foreign tax or banking rules
• Register or support a business presence overseas

Which IRS Documents Can Actually Be Apostilled?
Most IRS documents are computer-generated letters or tax returns without signatures or seals. These documents cannot be authenticated through the U.S. Department of State.
To be accepted for apostille, an IRS document must:

• Be an original, issued directly by the IRS
• Contain a wet (ink) signature from an authorized IRS official
• Be clearly intended for international or official legal use.

Apostille Eligibility for IRS Documents

What If My IRS Document Can't Be Apostilled?
If you're trying to apostille Form 1065, a corporate return, or a basic EIN confirmation, these documents are unfortunately not accepted for federal apostille.
However, in many situations you can use alternative documents that are eligible for apostille, such as:

• IRS Form 6166 – tax residency certificate
• Certificate of Good Standing – issued by the state of incorporation
• Certified Articles of Organization – obtained from your state’s Secretary of State

These alternatives are often more appropriate and widely accepted by foreign institutions.
If you're unsure which document is required in your case, we can help determine the best option based on your destination country and purpose.

What About Affidavits?
In limited cases, some clients attempt to apostille a notarized affidavit that references an IRS document.
This method involves:

• Writing a sworn statement explaining the contents of the IRS letter
• Notarizing the affidavit
• Apostilling the notarized affidavit at the state level

⚠️ Important to know:
The apostille applies to the affidavit, not to the original IRS document

• Many institutions abroad do not accept affidavits in place of official tax documents
• This approach is not recommended for formal legal or financial procedures abroad

Apostille for IRS Form 6166 – The Gold Standard
Form 6166 is the IRS's official Certification of U.S. Tax Residency. It confirms that a person or entity is a U.S. tax resident under an income tax treaty.
It is:

• Issued with an official IRS signature
• Printed on IRS letterhead
• Accepted by foreign tax authorities, banks, and government offices
• Fully eligible for apostille through the U.S. Department of State

If you need to demonstrate U.S. tax residency overseas, this is the document to request from the IRS.

Unsure If Your IRS Document Qualifies?
You can send us a scan or photo of your IRS letter for a free review. We’ll confirm:

• Whether the document qualifies for apostille
• What alternative options may be available
• What the next steps are if you don’t yet have the right paperwork

How the Apostille Process Works

• Send Your Document for Review

Upload or email a scan for verification.

• Mail the Original

If it qualifies, we’ll provide secure mailing instructions. Only original, signed IRS documents are accepted.

• Federal Apostille Submission

The document is processed through the U.S. Department of State in Washington, D.C.

• Return Delivery

Once apostilled, the document is shipped back to you with tracking.

Ready to Begin?
Upload your IRS document or use the contact form below.
You’ll receive a personalized response and quote within 24 hours.