if he uses monthly income affidavit method, it is only 40,000 THB (1065.- Euro) per month for the Non-Imm-O family visa and the Extension. His monthly 1700.- Euro pension is far above the required amount
you will be fine. And even if not: transfer your money back to your UK account from the Thai bank. Then use WISE to transfer it back to your Thai account, and choose as reason in the list "funds for longtime stay in Thailand". This transfer will be coded as having come from abroad
check your bankbook(s), also the old ones. Check the CODE under which the money was received. If it says FET or FTT, it's proof that the money came from abroad
Savannakhet discontinued issuing the 365-days multi entry Non-Imm-Family Visa when they went to the e-visa online system by January 2025. The Royal Thai Consulate in Savannakhet was the last one to offer this visa category. Other embassies had already discontinued issuing it by October 30 2023
the same if you apply for a 90-days Nonn-Imm-O Retirement Visa, the 800,000 THB can be on ANY bank account ANYWHERE in the World, as long as you can show the account is in your sole name and the deposit has been sitting in the account for THREE months. Only for the application to the 1-year Extension of the Stay Permit, the 800,000 THB must sit in a Thai bank account
the 500,000 THB deposit you need to prove for the application to the DTV, can be on ANY bank account ANYWHERE in the World, as long as you can show the account is in your sole name and the deposit has been sitting in the account for THREE months. You need to show 3 months of bank statements. That's a rule EVERY Thai Embassy worldwide is following, regarding the DTV
After you entered Thailand, you don't stay in their country “on a visa". You have gotten stamped in on a "stay permit".
As soon as you use the correct term "if your stay permit is valid for a minimum of one year" instead of the incorrect term "if your visa is valid for less than one year," the entire meaning of the sentence changes