Australians getting married in Thailand information

as provided by the Australian embassy (check for updates)
http://www.austembassy.or.th/abroad/getting_married_eng.php

This information sheet is to assist Australians on how to register a marriage performed in Thailand to ensure it will be recognised as a valid marriage in Australia. The Embassy cannot provide any further information on other issues, such as organising celebrants or venues. For information on a Thai spouse’s immigration to Australia contact the Immigration Section of the Embassy separately.

Why do I need to legally register my marriage?
A marriage in Thailand must be registered with Thai authorities to be a valid marriage under Thai law. A valid Thai marriage, between adults, will then be recognised as a valid marriage in Australia. If you do not properly register a marriage performed in Thailand with Thai authorities, you are not legally married, either in Thailand or Australia.

What do I need to do to register my marriage?

The marriage must be registered at the Amphur (or district) registrar’s office, in the Amphur where the marriage was performed. In addition to the normal requirements (about which you should seek advice from the celebrant), each Australian party to the marriage must provide their Australian passport, and complete the following documents and processes:

Statutory declaration
All Australians married in Thailand must complete a pre-printed, pro-forma, statutory declaration and have it witnessed at the Australian Embassy in Bangkok. This is a Thai government requirement, including that it only be done at the Australian Embassy, Bangkok (i.e. it cannot be done in Australia, elsewhere in Thailand, another Embassy or online). A fee of $20 is payable per declaration in Thai baht cash equivalent and service is on the spot.

Death/Divorce Certificates
If previously married, an original divorce or death certificate to demonstrate you are no longer married must be provided. You must bring original documents and also have the Embassy certify a copy for you. A fee of $30 is payable per certified document in Thai baht cash equivalent and service is on the spot.

Translation
You must have the statutory declaration and any applicable divorce/death certificates translated into Thai at a private translation agency. There are many in Bangkok who can do this in one working day. Fees vary.

Certification by Thai Department of Consular Affairs
After the documents have been translated they must be authenticated by Thai authorities. This takes 2 working days and a fee is payable. For information on this service you should contact:

Department of Consular Affairs
123 Moo 3, Changwattana Road
Kwang Toong Son Hong, Khet Laksi, Bangkok
Tel. (+66-2) 5751061, (+66-2)-5751057; Office hours: 08:30 – 15:30

Amphur Office
When you have completed the above requirements, you should go to the Amphur Office to register the marriage. You should take an interpreter to facilitate communication with the Amphur officials if neither party can speak Thai. You should generally make an appointment before proceeding to the Amphur. You should ask your celebrant/organiser to make these arrangements.

Important points:

Apart from dealing with the Amhur office, the above processes can only be completed in Bangkok, Thailand and you will generally need 3 working days in Bangkok for this.

For the Australian embassy Website here