Do the 90 days on a marriage NON-O visa start from entry into Thailand or from the visa issuance?

When you apply for a marriage NON-O visa, the 90 days start from the date you enter Thailand, not from the time you received the visa. It is important to enter Thailand within 90 days of obtaining your visa, as upon arrival, you will receive a stamp allowing you to stay for 89 days. If you wish to extend your stay beyond this period, you will need to apply for an extension.