OK, here's my question in a nutshell: My type B Visa expires in late January. Can I use a Thai tax return form and receipts, showing that I earned 40K baht per month in 2550, to extend it for another year based on supporting a Thai wife?

Here's the background to this question: I got a Type O marriage visa good for one year back when you only needed 200K in the bank. The next year, I extended/renewed based on having a job with a Work Permit, etc... I continued renewing/extending on this basis for the next couple of years.

I now want to change jobs when my current contract ends, but my Visa ends two months before my contract does! I don't want to work and stay illegally and I don't want to walk away from my current job before the end of the school year. So, can I change my Visa from a type B back to a typ O? And, if so, can I do it without an new job contract for the next year?

There is no visa change required for extensions of stay - you can change the reason for extension of stay without need for a new visa - just present the new paperwork at the normal extensions of stay time - in this case your wife will also have to be present. Check exactly what paperwork they want for the income proof; but it sounds like you will have it. Am not sure if there will be any problem with the work permit - you can work on family extension of stay so should be OK. Have not seen any reports of a need for proof on future earnings.

Thanks. I was pretty sure that that was the case.

I just hope that there aren't any dramatic changes before January!