The only way to jump off the O/A status is by invalidating the current stay permit. It CANNOT be done on Immigration.
You can ask your Immigration if they are willing to allow you the next annual extension with “reason” retirement or “reason” family, but normally this is not how it is done.
This is rather done by exiting Thailand without a re-entry permit. Then in either your home country or in one of Thailand's neighbor countries like Laos or Vietnam, you can apply for a 90-Days Non-Imm-O family or retirement visa.
Alternatively, MUCH EASIER, you EXIT Thailand without a re-entry permit, and re-enter Thailand visa-exempt. You will get stamped in for 60 days.
You visit Immigration and apply for the "change of visa type" from the visa-exempt entry to the initial 90-days Non-Imm-O Visa (Married or Retirement).
You need to show a proof of finances, which either is a proof of a Thai bank deposit or a legalized income affidavit.
You would need to show (in case of retirement) that you ALREADY hold 800,000 THB in your Thai bank account, or show (in case of married) you already hold 400,000 THB in your Thai bank account. You need to prove that the money came from abroad. There is no seasoning requirement for the deposit at this point.
You also need to show a rental contract.
You can try to use your 12-months of transfers bank statement when applying for the "change of visa type", as the rules officially accept either deposit OR income.
Or, if your country’s embassy in Bangkok still issues income affidavits, use that to prove a monthly income of a minimum of 65,000 THB.
The application to a change costs a fee of 2000 Baht.
The 90-days Non-O visa will be issued for "14 days under consideration", after this waiting period you visit Immigration and pick up the visa-stamp.
And up from 30 days (or 45 days on some Immigrations), as soon as the deposit has seasoned in your account for 2 months, you can apply for the "1-year extension of the stay permit" on Immigration, which costs a fee of 1900 Baht.
The biggest advantage of this step: you jump off the mandatory insurance requirement. Now you are free to choose any insurance company, or keep self-insured.
You CANNOT invalidate the O/A Extension of Stay on Immigration. The invalidation is a MUST BE part of the process. You NEED to EXIT Thailand at least ONCE. You can visit your Immigration and ask which steps you must undertake in order to achieve a Non-Imm-O status and the subsequent 1-year extension of stay permit. MAYBE they offer you an easier path.
Ask your Immigration how to proceed. Find the requirements for the "change" from a visa-exempt entry to a 90-days Non-O Visa on this website. Marriage is number 6, and Retirement is number 9
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