nope you show that you stay/live IN the area where you're applying for the extension
Showing you own a condo in Phuket isn't gonna cut any ice trying to get a yearly extension in Chiang Mai
And you're going to need to get a TM30 filed on the address where you're staying in Chiang Mai as well as lease, maybe land lord thai i/d, house book listing,
this is a generic list of what can be required for extensions based on retirement, it is NOT office specific and Chiang Mai may require different things, BUT this will get you close ๐
In Chiang Mai you can apply for a new extension when you have 45 days or less left on your current stamp <meaning from 45 days before right on down to the day your current stamp expires
Obviously the closer to the expiration date you apply the less chance you have to correct any issues (missing documents, etc) that come up in the application process. ๐ฎ
As I said you can apply right up until the date your stamp expires (and if it expires on a weekend or a day the immigration office is closed but you go the very next day they're open you can even apply then too without getting an overstay fine) ๐
The worry is you don't have every document, copy, bank statement, bank letter, updated bank book, TM30, lease, etc that you need and you run yourself out of time ๐ So that burden is on you to get it right in the time you have left ๐
As posters correctly stated at most offices you can file for an extension of stay when you have 30 days or less left on your current stamp and a few offices (Bangkok, Chiang Mai, Buriram Samut Prakan, Phuket, and others) allow you to do it when you have 45 days or less left on your stamp
What you should do is go to your immigration office and get the hand out listing the requirements needed at that specific office for the marriage extension and while you're there ask them what's the earliest you can file for the year extension
That extension is issued for the real reason of "เธเธฃเธเธตเนเธเนเธเธตเธงเธดเธเนเธเธเธฑเนเธเธเธฅเธฒเธข" <- which says in the instance of living out the end of your life ๐ฎ (now you see why they call it "retirement" in english ๐ )
and
there is a clause that says เธกเธตเธญเธฒเธขเธธเนเธเธดเธ 50 เธเธตเธเธถเนเธเนเธ <- be 50 years or older
They won't let you switch to that extension until you hit 50
Now you say you're on a yearly extension based on marriage to a thai national, so you might ask them if you could get the 60 day visit thai family extension and that could "buy you the time" until you turn 50 so you could apply for the year extension based on retirement after that 60 days winds down