Any foreigner who are legally married to a Thai citizen are eligible to get a long-term visa to stay in Thailand that can be renewed on a yearly basis, this particular visa is under the Non-Immigrant-O(Other) visa also known as “Thai Marriage Visa”.
In obtaining this visa the applicant must lodge application together with all the complete necessary documents in a Thai Embassy and normally may take from 2 to 5 working days depending on the processing consul office.
For those who wish to take up marriage visa in Thailand, they will require these documents;
Obtain a 90-day visa or a year’s non-immigrant O visa from your country prior to the application for the marriage visa in Thailand.
After receiving your non-immigrant visa, travel to Thailand for its activation.
Prepare the required documents for conversion of the non-immigrant O visa to the Thai marriage visa
One can seek extension within the last thirty days of the ninety days permit.
Submit the visa extension certificate to the Immigration Office along with all the important documents for the application. As for the processing period, it is likely to take a month.
The best way to get guidance on your specific legal issue is to contact a lawyer.