From tourist visa to yearly extension (retirement)

Here in Chiang Mai, they won't do give 15+ months visa extension in one appointment. Instead, they want you to convert to a 90-day O visa and then return during the final 30 days of that visa to obtain a 1-year extension due to retirement. Each step requires a fresh letter from either the Thai bank and/or the consulate. You'd think they'd welcome the opportunity to reduce their workload, but no!

It would help if the OP told us where he planned to live. Unfortunately, local practices do differ.

The Thais do Public Service well -- and each Office appears to be it's own little fiefdom