Do bank statements need to be dated on the day of applying for a marriage visa in Thailand?

You should have come to this FB group first to ask for advice. You’ve got it now.

@Fraser *****

okay,

You are here on a 30 day visa exempt entry stamp, you NEED to be on a Non-Immigrant Type O visa to get an extension based on marriage.

SO

you're going to need to apply for a 90 day Non-O visa from section C-1 first. Then you're going to wait the two weeks, go back and get it stamped into your passport.

Then you're going to wait another 6 weeks or so and then go back and apply for the year extension based on marriage. <- and yes at that time you will need to get a new bank letter and update your bank book AND have all the photos, paperwork etc again..

Where are you applying for this 'marriage visa'?

If you're applying for a yearly extension of stay based on marriage at the immigration office you need a bank letter (usually less than a week old) AND you need to update your bank book on the day you go apply for the extension so they can see the money is still in the bank.