you have to understand that getting a tourist visa to thailand from a consulate has its own set of requirements (which now include showing proof of funds)
AND
entering thailand either free stamp (visa exempt) or on a valid tourist visa have their own set of "entry requirements" (like James outlined) <- which may or may not be asked for when you stamp into the country.
and this was the answer I'd given on the original post
You (or the land lord) would file a TM30 showing you're registered as living/staying there.
You would check with your immigration office there to see if you need to file a TM28 <-change of address form (some offices require it still)
You would get the hand out from that office listing the requirements at that specific office for the extension you're applying for.
IF you are applying for a new yearly extension FROM an existing extension (where you used banked money method) you would need a 12 month print out of the detail transaction report so the immigration office can check that you met the seasoning requirements of the extension you're on now. You need the "standard" bank letter and to update your bank book the day you apply as well.
There are OVER 80 immigration offices in the country and it would behoove you to go to your new office, check about that TM28 change of address form and get the hand out listing the requirements there at that office
This is a GENERIC list of the requirements based on retirement that will work most of the time but it is NOT office specific (which is why I mentioned 2 times to go get the hand out at the specific office you're going to apply for the extension at 🙂 )
Remember even holding a valid tourist visa to thailand (that you got before you came here) doesn't mean you get IN to the country, only that if they let you in you get in for the 60 days that visa allows
Either location in Chiang Mai (the main office by the airport OR the satellite office in Central Festival Mall) will issue 30 day extensions on 60 day free stamp entries
There is not one verifiable post about anyone being required to show proof of tax payments when entering the country 😕
There are a few posts of people from certain nationalities who were asked to show the documentation they used when they applied for their DTV but it is the exception rather than the norm.
Most everyone of the tens of thousands of people on DTV's just show up with the PDF print out and their passport and get in without any issue at all