After a 4 year hiatus, I am about to apply for a Visa for a long stay in Thailand. I have a wife and kids in Thailand but most of us were all outside for the 4 years. The wife and kids of course have Thai passports, so no problem there. I intend to apply for a non immigrant O, which is only good for one entry. However I do have to leave after about a month and likely also two months for about a week each time before coming back.

 

Is it possible to add multiple entries at immigration Thailand? 

Why not just apply for a Non Imm O Multi entry Visa, valid 1 year, multiple 90 day entries.

 

If you obtain the single entry Non Imm O, valid 90 days, you can obtain a multi re-entry permit from Immigration (3,800 baht) but that will not extend your permission to stay beyond the 90 days.

Dependent upon where you are apply for the non-o visa you should be able to get multiple entry visa instead of single entry.

You could only get a multiple re-entry permit that would only keep the remainder of the 90 day entry from the visa valid at immigration. It adds no days to your total stay.

You could apply for a one year extension of stay at immigration based upon marriage during the last 30 days of the 90 day entry. You would need 400k baht in a Thai in your name only for 2 months or proof of 400k baht income.