You have to do things they way they are done, not the way you want them done.

When you apply for a non-O visa and you're on a tourist stay, you lose any extra days because it's not an extension, it's a conversion.

You cannot apply for the extension until you have 30 days or less left, or 45 days or less left at some offices. Since you start with 90 days, you cannot immediately apply.

You will have to submit whatever paperwork they ask for. You should get the list from immigration. If you already have a lease, you don't need a new lease. You use the one you have.

The embassy instructions are to print out the visa and hand it over with your passport. Without the printed visa, the immigration officer may make a mistake and stamp you in with a 60 day visa exempt stamp, since that's mostly what they do all day.

And ALWAYS check your passport after leaving passport control to ensure you received the correct stamp. It's very easy to fix then and there, and very difficult if not impossible to fix later.

Most immigration offices allow when you have 30 days or less left.

Some immigration offices allow when you have 45 days or less left.

A couple allow when you have 7 days or less left.

Since you have not indicated what immigration offices, your question is not possible to answer.

@Stephen ********

He cannot use the pension for anything, because the embassy will not certify it. But during the entire first year he can transfer at least 40,000 baht (65,000 baht for retirement extension) to his Thai bank account from overseas. Then for next extension if he can show 12 monthly transfers, the immigration office may accept that.

He would need to check with them before starting down this process, as some immigration offices will not accept international transfers for marriage extensions. The only monthly income some accept is embassy certified income, or proof of income from a work permitted job inside of Thailand.

@Yaoyu **********

You can buy it either. But you need to understand what a re-entry permit is.

A re-entry permit keeps your existing permission of stay stamp alive if you leave Thailand. If you buy it before your extension, then it's only valid for the stamp you have at the time you bought it. If you buy it after your extension, then it's valid for that extension. All it does is make your existing stamp not be cancelled. It doesn't do anything special, there's no trick with it. It's very simple.

@Greg ********

Waste of money and also probably forcing him to use an agent next year too.

You don't need to do anything special.

Arrive with non-O, open your bank account and deposit your money.

At the airport on your way out, get a single re-entry permit for 1200 baht.

When you return you will be stamped back in based on your original entry stamp. Make sure you are back before that expires.

Then go to immigration and apply for your extension.

Immigration does not require proof of onward travel to enter Thailand. But you are applying for a 90-day visa, so you must give them information for a flight leaving Thailand within 90 days. It doesn't ask you for a TICKET leaving Thailand, it just asks for a flight. Go find one and put it in.

Why not give basic information, like where you are applying in Thailand?

Most immigration offices allow when you have 30 days or less left.

Some immigration offices allow when you have 45 days or less left.

A couple allow when you have 7 days or less left.

You do what you are supposed to do. You get the visa from the Thai embassy in London before you go to Thailand. That's how visas work.

Then when you arrive in Thailand you will have the non-O visa and can open a bank account.

The problem you are going to have is that you cannot use your monthly income for your extensions. The first 1-year extension based on marriage can only be obtained using 2 financial proofs.

1) Embassy certified income. The UK embassy has not offered this for many years.

2) Proof of 400,000 baht in your Thai bank account that has been there for 2 full months at the time of your extension application.

Because 1 is not available to you, only #2 is available to you. There are no other options for you.