Thai Document Legalisation in the U.S. — 2026 Guide

Thailand does not use the apostille, and it applies a rule no other country in this directory does. A Thai mission will legalise a U.S. document only if it was issued within that mission’s own consular district. A certificate from Texas cannot be legalised in Los Angeles, however close you live to it.

Quick facts

There is a second condition just as firm: missions legalise official U.S. documents only after the U.S. Department of State has certified them. A state-level certification alone is not enough.

The chain

For filing by post, missions ask for a legalisation petition form, your identification, a notarised signature on their own form, and a prepaid express return envelope.

How to prepare a document

1. Identify which state issued the document, because that decides the mission.
2. Obtain the state certification, then the federal certification in Washington.
3. Complete the mission’s legalisation petition form.
4. Have your signature notarised on the form the mission provides.
5. Send the original, the identification copy, the fee and a prepaid express envelope.
6. Arrange the Thai translation afterwards, normally in Thailand.

Required documents

• Original document certified by the U.S. Department of State.
• Completed legalisation petition form.
• Thai identity card or passport, or a foreign passport or state identification.
• Notarised signature on the mission’s form for postal filings.
• Prepaid express return envelope.
• The fee in the accepted form.

What the missions do

They issue passports and identity cards, handle civil registration, legalise documents, issue visas and assist Thai nationals in difficulty.

Additional notes

Work out the jurisdiction first

This is the step that wastes the most time. The mission is chosen by the document’s origin, not by your address.

Federal certification takes weeks

Build it into the timetable. It is the slowest stage and it cannot be skipped.

Translations

Thai authorities generally want the translation made and legalised in Thailand. Ask before paying for one here.

Order two copies

Thai offices keep what they receive, and this chain is long enough that you will not want to repeat it.