What do I need to prepare for re-entering Thailand on a multi-entry retirement visa after an 8-week trip to the UK?

okay the O/P is NOT asking if he will need a re-entry permit so the type of visa/extension he has isn't important in the least (to US or him) :O

As long as you return to thailand before the date your re-entry permit expires you'll get stamped in until that date

As far as what will you need to re-enter the country? Well watch for the re-entry request requirements closer to when you are fixing to come back (Check the website of the thai consulate in your country and/or watch the thai news about it)

Right now you need

- 100K USD in covid specific insurance valid for the duration of time you'll be stamped in for

- a negative covid test within 72 hours of flying in

- a Certificate of Entry from the Ministry of Foreign Affairs

- a 14 day booked quarantine at a gov't approved ASQ facility.

NOW whether those will be the same entry requirements when you're comin' back, who knows.

>multi entry retirement one year visa

What is this exactly? Can you post a picture of this visa with any confidential information removed?

There are three things that people call "multiple entry retirement one year visa":

- A non-OA visa

- An extension of stay based on retirement with a multiple entry re-entry permit

- A multiple entry Non-O visa (I think a handful of embassies are still selling this).

What you got would let us give you the right answer