What are the requirements and process for applying for a 1-year retirement visa in Thailand without an agent?

Question. If you are married then you just need 400k baht is my understanding. Can you also draw that down or have to keep it at 400K?

I have a question. Do both my husband and I have to each put 65,000 into our account so 130,000 each month or ?

𝟭 - 𝗜𝘀 𝗺𝗲𝗱𝗶𝗰𝗮𝗹 𝗶𝗻𝘀𝘂𝗿𝗮𝗻𝗰𝗲 𝗿𝗲𝗾𝘂𝗶𝗿𝗲𝗱 𝗳𝗼𝗿 𝘁𝗵𝗶𝘀 𝘃𝗶𝘀𝗮?

no there is no medical insurance requirement for a Non-O visa/extension

𝟮 - 𝗛𝗼𝘄 𝗹𝗼𝗻𝗴 𝗱𝗼 𝗜 𝗻𝗲𝗲𝗱 𝘁𝗼 𝘄𝗮𝗶𝘁 𝗮𝗳𝘁𝗲𝗿 𝘁𝗿𝗮𝗻𝘀𝗳𝗲𝗿𝗿𝗶𝗻𝗴 𝘁𝗵𝗲 𝗿𝗲𝗾𝘂𝗶𝗿𝗲𝗱 𝗳𝘂𝗻𝗱𝘀 𝗯𝗲𝗳𝗼𝗿𝗲 𝗜 𝗰𝗮𝗻 𝘀𝘂𝗯𝗺𝗶𝘁 𝗺𝘆 𝗮𝗽𝗽𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻?

You need to "season the funds" in a thai bank account in your name only for 2 months (date to date) before you apply for the yearly extension

𝟯 - 𝗔𝗳𝘁𝗲𝗿 𝘁𝗵𝗲 𝗲𝘅𝘁𝗲𝗻𝘀𝗶𝗼𝗻 𝗶𝘀 𝗴𝗿𝗮𝗻𝘁𝗲𝗱, 𝗱𝗼 𝗜 𝗻𝗲𝗲𝗱 𝘁𝗼 𝗸𝗲𝗲𝗽 𝘁𝗵𝗲 𝗳𝘂𝗹𝗹 𝗮𝗺𝗼𝘂𝗻𝘁 (𝗼𝗿 𝗽𝗮𝗿𝘁 𝗼𝗳 𝗶𝘁) 𝗶𝗻 𝘁𝗵𝗲 𝗮𝗰𝗰𝗼𝘂𝗻𝘁, 𝗮𝗻𝗱 𝗶𝗳 𝘀𝗼, 𝗳𝗼𝗿 𝗵𝗼𝘄 𝗹𝗼𝗻𝗴?

You need to keep the 800K baht in the bank account for 3 months after your yearly extension is granted and after that the balance can't go below 400K for the rest of the year (before you get it back to 800K 2 months before your next yearly extension

You should GO to your immigration office and get the hand out listing the requirements for the yearly extension based on retirement at that specific office well before you're going to go for the extension, that way you know what copies, documents, bank letter, statement, updated bank book, map, photo, etc you need to get together