@Pete ******
let's assume I am a tax resident in Thailand:
1. Is a UK, company or state pension paid into a Thai bank account subject to Thailand tax. Please bear in mind everyone in the UK is allowed a personal allowance before any tax is due of at least £12,570, some have a higher personal allowance. So although £12,570 is taxable income, no tax is due in the UK as you are allowed that, only if you have income above your personal allowance is that income taxed. So if you had £12,571 income, you'd be taxed on £1, and 20p tax would be due to the HMRC. I can't understand why you'd be taxed on that income in totality in Thailand.
2. You are allowed to take 25% of your pension pot tax free in the UK, either has one lump sum or as a series of drawdown payments. Again, I can't understand if you drew down your 25% in monthly installments and had it paid into your Thai bank account, why that would be subject to Thailand tax.
3. I've never heard on any forum anyone say they've had to pay tax on their 400k, 500k, 800k requirement for visa deposits into a Thai bank.
And this, if you don't bring it in in the year it was earned, rather leave it in your UK bank account and bring it in the year after, how on earth would the Thai HMRC be able to police a deposit paid into a Thai bank account was earned in the UK yesterday, last month, last year or 5 years ago?