What should I do about my 90-day report for my retirement visa if I return to Thailand later?

Yes it re sets when you return Joe you have a re entry permit

Only if you get a reentry permit before you left I think you'll find

I have a retirement visa w multiple entry . I can stay out of the country as long as I want . Did you pay for the multiple entry visa ?

You're worried about the wrong thing. A 90 day report is done when you spend 90 days in a row in Thailand. When you're not in Thailand you're not spending 90 days in a row in Thailand, so there is no 90 day report. If you left at 89 days every time you'd never do a 90 day report because you never spent 90 days in a row in Thailand. When you return to Thailand you start over at day 1 because it's only consecutive days in Thailand that matters.

What I'm wondering about is you said you just got your retirement visa while you were in Thailand. A retirement non-O visa is only valid for 90 days. So if you got that then it will expire at the beginning of September and you will have to start all over again.

Or did you already do the 90 day in Thailand and then apply for the 1 year extension and that's what you are on now? If you are on the 1 year extension then you don't need to worry about the timing.

The final thing to ask is did you get a re-entry permit before you left? If you don't get a re-entry permit before you left your visa/extension is no longer valid as it's void the moment you leave the country without the re-entry permit.