What is the process for getting a new visa after canceling my work permit in Thailand, and can I convert to a marriage or retirement visa without leaving the country?

Go see an agent

The day your WP is canceled you have to leave.

There is no grace period.

You could apply for an extension , be denied and given 7 days to leave if you can prove exit within that time.

SOME offices may allow a "change of reason for extension" the same day as you are canceling your extension and do it all at once.

Not all offices will allow, currently for example Phuket will not allow that change in most cases.

There may be a "special case" scenario.

You will have to leave and start over.

NOTE: if you stay beyond your WP cancelation you are on overstay.

Your employer could allow you to stay longer by scheduling the cancelation a short-time in the future, a couple days or weeks.

Then immigration would allow you to stay until that date by seeing them with the proof of upcoming cancelation.

This is the best scenario if you are on good terms.

That would depend on whether or not your work permit was canceled in advance with the cancellation date sometime in the near future. Typically you take the letter from the department of labor and then go to immigration and have your new extension date inked in. At that point if you qualify you can ask for a change of extension reason. Otherwise you're leaving by midnight.

Sorry, if possible why not go ask these questions at immigration. As we know every office is different and sometimes even the same office is different day to day. 🙂 Ive always had good luck discussing issues with them.

The easy way to do this is to cancel your work permit, cancel your existing extension of stay and immediately apply for an extension of stay based on either retirement or marriage, you skip the applying for a visa part. To make it work you must of course meet the requirements of whichever extension of stay you wish to apply for so before you do anything visit your local immigration office and get a handout of their requirements. The day you cancel your work permit your extension of stay based on it is no longer valid so needs to be cancelled and if you don't have all your ducks lined up you'll have to leave the country.

Years ago I was told you could not get the retirement Visa unless you left the country came back in on a 30-day exemption which was the amount they gave you back then. Then you could go through the process to get the retirement Visa. I dealt with an agent unfortunately she's no longer in business she made it happen that I didn't have to leave the country within a couple of days my business Visa was converted to a retirement Visa not sure if you can find somebody that can do it for you now