When should I apply for a Wife or Retirement Visa before my 90-Day Non-O expires, and what are the differences between these visas?

I opted for a Non-O spousal visa. A bit more paperwork on the extension proving the legitimacy of your relationship, but the financial requirement is half the amount of the Non-O based on age. And, should your ever want to do some work here and obtain a work permit, you can do that under the visa where you are supporting a dependent. Best of luck to you.

For either you do need money in your Thai bank account in your name only. For the Thai wife extension the amount is a minimum of bt400,000, and it can come from anywhere. For the retirement extension the amount in your Thai bank account in your name only is bt800,000, and it must come from an overseas transfer. You can't just deposit bt800,000 in your account like you can do for the Thai wife extension. The other big difference is under a Thai wife extension you can get a work permit, and work in Thailand. Under a retirement extension you can not work at all, and can be deported if you are caught working, even helping your wife in her work. Also, under the Thai wife extension there is no insurance requirement, although it is a good idea to have health insurance. Now, there are two types of retirement extensions, a type O, with no insurance requirement, and a type OA/OX that does require health insurance in order to extend it. You get the type O inside Thailand, and the type OA/OX outside Thailand. Those are the main, and important differences.

In both cases the money has to be in your Thai bank account a minimum of two months before you apply, and you can apply 30 days before your visa expires, and at some immigration offices, like Chaeng Wattana up to 45 days before. Whatever date you chose your year extension will start from your visa expire date, even though with the Thai wife extension you will have a 30 day under consideration stamp and date to return to get your extension. It will still be dated when your original visa expired.

Firstly, it's an extension , not a visa ,and you apply before your visa expires.

Secondly, I'll give you a clue.. you need a Thai wife for one of them, same as your visa. The other one you need to be 50 years old minimum and don't need a Thai wife..

Good Idea ask your local Embassy