Certificate of Residency (sometimes referred to as a letter) from IO based on tenants current TM30 is required. (Same form is used to register or sell a vehicle).
The form is free if you can wait a week or 500THB if you want the document straight away.
Your local IO should be able to assist and advise your tenant of the process.
The most recent Retirement Financial Criteria is contained within RTP (Immigration) Order # 35 / 2561 (2019).
Your local IO should be able to advise you how to switch from deposit to monthly income?
But as previously stated as long as you keep to your current conditions until Apr 2023 and can evidence the required monthly income there should be no issues?
Neil Hart....This is the UK legislation applicable to your situation. Each country will have its own legislation. Simply put it's about "child protection".