IRS Form 6166 · Thailand
IRS Form 6166 Legalization for Thailand
Route, timeline, translation and price for using a IRS Form 6166 in Thailand — based on the official Hague Convention status table.
Quick answer
Thailand requires embassy legalization. Your IRS Form 6166 needs U.S. Department of State authentication, then Thailand embassy legalization — 15–17 business days with us, both steps included. Certified Thai translation required.
- Route
- Authentication + embassy legalization
- Hague member since
- Pending — 28 February 2027
- Issuing authority
- Internal Revenue Service
- Translation
- Certified Thai translation required.
Is Thailand a Hague Convention country?
Not yet. Thailand acceded to the Apostille Convention on 30 June 2026, but it does not enter into force until 28 February 2027. Until then, documents still need U.S. Department of State authentication followed by legalization at the Thailand embassy. If you’ll be filing after that date, tell us — the route changes to a single apostille.
The route to Thailand
A IRS Form 6166 is issued by Internal Revenue Service, a federal authority, so it is authenticated by the U.S. Department of State in Washington, D.C. — never by a state office. For Thailand, the Department of State’s authentication is then legalized at the Thailand embassy or consulate.
People most often send documents to Thailand for marriage, retirement visas, work permits. Receiving offices set their own requirements, so confirm what yours asks for — we’ll help you read it.
About the IRS Form 6166
How to apostille IRS Form 6166, the U.S.
You obtain this from Internal Revenue Service. We can’t request it on your behalf, but once you have it, we handle everything through to delivery in Thailand.
Timeline and price
| Stage | Time | Notes |
|---|---|---|
| Department of State authentication + embassy legalization | 15–17 business days | Both steps included; the Thailand embassy step cannot come first |
| Certified translation | Alongside | Ordered with the authentication so nothing waits in sequence |
| Return shipping | 1–3 days in the U.S. | Tracked courier; worldwide delivery available |
Price: $399 per document, government fees and U.S. shipping included, embassy legalization included.
Translation for Thailand
Certified Thai translation required. We coordinate certified translation alongside the authentication so the document arrives ready to file.
How it works
Confirm the route
Tell us you’re sending a IRS Form 6166 to Thailand. We confirm route, price and timing before any payment.
Get the document to us
Ship it to our processing office, or to any of our U.S. offices and we route it internally.
Pre-submission review
We check it against authentication requirements to catch the problems that cause rejections.
Department of State
Hand-delivered to the Office of Authentications in Washington, D.C.
Thailand embassy legalization
The authenticated document is presented to the Thailand embassy or consulate.
Certified translation
Arranged alongside so it arrives ready to file in Thailand.
Delivery
Returned to you by tracked courier, or sent directly to your recipient in Thailand.
Sources: HCCH — Apostille Convention status table (updated 30 June 2026) · U.S. Department of State — Authenticate Your Document.
IRS Form 6166 for Thailand — FAQ
Is Thailand part of the Hague Apostille Convention?
It has acceded, but the Convention only enters into force for Thailand on 28 February 2027. Until then, embassy legalization is required.
How long does it take to prepare a IRS Form 6166 for Thailand?
About 15–17 business days for Department of State authentication plus Thailand embassy legalization, both included. Certified translation runs alongside.
How much does it cost to send a IRS Form 6166 to Thailand?
$399 per document, with government fees and U.S. shipping included. The embassy legalization step is included. We confirm your exact price before any payment.
Do I need a translation for Thailand?
Certified Thai translation required. We can arrange certified translation with your order.
Can you obtain the IRS Form 6166 for me?
No — you obtain it from Internal Revenue Service first. Once you have it, we handle the rest.
Do I have to be in the United States?
No. Most Thailand orders are handled entirely by mail, and we can ship the finished document anywhere.
Related: IRS Form 6166 — full guide · All documents for Thailand · Apostille vs. embassy legalization · Why apostilles get rejected
Ready to start?
Order online in minutes, or call and we will walk you through it. Federal documents from anywhere in the U.S. — one flat price, all government fees included.