Can I use the 400,000 baht deposit for other purposes after applying for an extension based on my Thai wife?

Best is to keep your deposit all the year long. They don’t like you use it, especially with a thaï wife extension. But, of course, up to you !

Okay so the consensus (as much as there ever is one on immigration stuff) IS

the posted police order states that you need to bank the 400k baht for 2 months before you apply for your extension and there is NO mention at all of the money needing to stay IN the account during the 30 day under consideration period.

I would plan on leaving the money, BUT if they don't tell you to update your bank book and bring it back when you go to get the year extension inked in after the 30 day stamp runs down it means they don't enforce that "made up rule" at the immigration office where you go to.. Chaengwattana DOES enforce it

Ask at your immigration offoce

Thai immigration may ask to see the bank book one month after your interview while your application is UNDER CONSIDERATION.

Then you can use the money...but must top it back up to 400,000 TWO MONTHS before your next extension.

Yes, BUT some Immigration officer can ask to keep the money in the bank during the under consideration period and show your bank book again at the end of these 30 days