I have just registered for COE for phuket sandbox. I have booked hotels and have insurance etc. I left Thailand on March 18th last year. I arrived with visa exempt 30 days and extended it for another 30 days. I am retired now and this visit, starting 23rd July, I would like to stay for 3 months. I believe this is possible. What sort of documentation will I need? Eg. I believe I must show proof that I can support myself financially. I stupidly? booked a flight from UK with a 3 month return. I can alter the return flight but I think I will be charged for this. Any help or ideas welcomed. 

From the UK you should be able to get a single entry non-O based on retirement.  That give a 90 day entry.    Info from the Embassy website;

 

Non-Immigrant Type O (Retirement (pensioner aged 50 or above with a state pension who wants to stay in Thailand for no longer than 90 days) - single entry only)

• Financial evidence e.g. A copy of pension statement if the applicant is a pensioner, or a copy of 1-month bank statement showing your income from pension, or 3-month bank statement of at least £10,000
• Confirmation of legal residence in the UK or Ireland

1 hour ago, Petethefeet said:

I am retired now and this visit, starting 23rd July, I would like to stay for 3 months.

 

How risk averse are you? Least paperwork/hassle:

 

visa exempt (45 days) > 30 day extension > 60 day covid extension (If covid extensions granted which IMO they will be) = your 3 months+