This is all literally the BARE MINIMUM information you can get from a single google search or by looking at the website of a Thai embassy.

@Will ********

it's not. Only at 2 locations

Government proposals are a dime-a-dozen in Thailand and you never hear about 99% of them again

@David ******

there's an end date field in the new system but it's not a required field. Generally a TM30 is good forever until a new one is filed (or for some offices until you leave Thailand).

You can't date a TM30 to the past, but it doesn't matter because a new TM30 replaces any existing TM30. Just ask for a new one effective today and you won't have any issues.

@Mark ********

If he was going to be getting an extension then he would need one, but otherwise not

First of all, customs has nothing to do with any of this. Customs is about what you are bringing into or taking out of a country.

Immigration and passport control are the ones who have to do with your permission to stay in a country. You cannot do anything at the airport, there is no immigration office at the airport. You can go to the immigration office and apply for a 30-day extension when you have 30 days or less left. It will cost you 1900 baht and a bunch of paperwork.

Official and legal answer: ALL property owners in Thailand are required to report the arrival of a foreigner that is staying there within 24 hours. This is the TM30.

Realistic answer: Will you be going to immigration to apply for an extension or any other service? If you won't be going to immigration and will just be leaving Thailand within 60 days, it's not something you need to worry about.

@Stephen ******************

You can't switch reasons like that. You are already on a non-O visa, so you cannot apply for a different non-O visa. If you want to switch to retirement you would have to either leave and return without using your visa (might not be possible while your multiple entry visa is still active) or you would need to apply for the 1-year extension based on marriage and then next year when you are due for an extension you could apply based on retirement instead. But you can't switch from non-O marriage to non-O retirement, and you cannot switch from non-O marriage to extension based on retirement. You can only switch from one extension to a different extension.

@Zamawelase *******

Yes they do. They check the computer and if what you say doesn't match they ask for a physical copy