The main reasons why it’s difficult to complete everything within 90 days are:

• Obtaining a Certificate of No Impediment (Single Status Certificate):
  If it’s not prepared in advance from the foreigner’s home country, most countries cannot issue it in Thailand.

• Opening a Thai bank account:
  Without holding a Non-O visa, it has become very difficult for foreigners to open a bank account (since 2025), as Thai banks have tightened regulations due to concerns about scam accounts and mule accounts.

A safer and more reliable option

1. Register your marriage in Thailand first:
   Prepare all required documents for the foreign partner — such as the Certificate of No Impediment, identification documents, etc. — and check with the district office (Amphur) in advance about any additional requirements.
   
2. Return to your home country to apply for a Non-O visa from a Thai embassy:
   Applications are now fully online. This method is easier and more secure than trying to change visa status while staying in Thailand under a Visa Exemption.
   
3. Re-enter Thailand with your Non-O visa:
   Once you have the visa, it will be much easier to open a Thai bank account, which is necessary when applying for a visa extension later.

If you still want to complete everything within 90 days, you must be extremely well-prepared

• Prepare all documents in advance, especially those from the foreign partner — such as the Certificate of No Impediment, passport, and any documents requiring official legalization by the home country.

• Translate all foreign-language documents into Thai and have the translations certified by the Thai Ministry of Foreign Affairs (Department of Consular Affairs).

• Make multiple appointments — with your country’s embassy in Thailand and with the local district office where you plan to register your marriage (some offices may not accept foreign marriages or may have long queues).

• You’ll need two witnesses at the marriage registration.

• Opening a Thai bank account is now much stricter. Most banks require a Non-O visa and a Letter of Residence for Foreigners issued by the Immigration Bureau or local authorities.

• Some embassies in Thailand do not issue Certificates of No Impediment, meaning the document must be prepared in the home country before traveling.