Can I repeatedly enter Thailand with a multi-entry Non-OA retirement visa without applying for a new visa?

You don't need new insurance every time you need 1 year insurance for full length of visa.

If you travel back to Australia frequently, you're better off getting a new OA (or better still an OX) every two years. This method there is no requirement to transfer money into a Thai bank account. You will need the ongoing insurance, but under the changed rules, you just need a minimum US$100,000 insurance. There is no requirement now for the 40,000 baht outpatient component, which was a problem before. You can use home country insurance, or if declined, you can use home country assets (property, super, shares etc).

I think if I use an actual valid Non-OA visa that it will be easier to explain the workings

This is a Non-OA from the Sydney thai consulate, the consulates in Oz are NOT on the eVisa system so you still send your passport to them to get the visa sticker stuck in.

This OA was issued on 2 Feb 2022, and is valid until 1 Feb 2023,

As you can see in number of entries below the issue/valid dates it is MULTIPLE entry.

This means the holder can enter/exit thailand as many times as they want during the validity of the visa itself (a year from the date it was issued) and every entry will get them stamped in for a NEW year <- OR as long as their mandatory health insurance is valid for (up to a year).

You can also see the thai stamp and date written at the bottom of the visa sticker ประกันสุขภาพครอบคลุมถึงวันที่ <- Health insurance coverage up until 19 Mar 2023) <- THAT controls how long a person will get stamped in when they RE-ENTER thailand on the visa while it is valid.

So at this time, this person can enter/exit thailand all they want and every time they will get stamped back in until March 19th 2023. <- the expiration date of their current insurance.

IF they want to get the "second free year" of stay out of this visa they would need to RENEW their health insurance for another year, exit the country on or before the 1st of Feb 2023 <-the expiration date of their VISA, and they'd get stamped back in for as long as their new policy was good for (in all likelihood March 19 2024 <- because renewing an insurance policy doesn't change the expiration date just the year)

NOW it needs to be said, IF they did exit/re-enter just before the visa sticker expired AND if they did have a new year insurance policy, should they want to exit/re-enter during that "second year" (after the VISA itself expired) they would need to buy a re-entry permit to keep that entry stamp 'alive'. Failing to do that would cancel their re-entry stamp when they stamped out of the country. If they did get a re-entry permit when they came back they would be stamped in until the date on it (NOT a whole new year because that's ONLY if the visa was valid and it expired). All you get AFTER the visa itself expires when you come in on a re-entry permit is stamped back in until the expiration of the previous entry stamp. It adds NO time to your stay anymore.

AFTER that time runs out, you either go back to your country and BUY a new OA and start all over

OR

You go to the immigration office with proof of funds, proof of insurance and apply for a year extension for 1900baht <- which you can do year after year if you want to

Sorry, it seemed like a good idea when I started writing it but after reading it maybe it was not as clear as I had hoped. 😕 Perhaps some will find it useful.

Nope, you are confusing the entries you can make while the year-long, multi-entry VISA <- the sticker or PDF file is valid which would stamp you in for a new year when you re-enter, AND the stamp you would get AFTER the visa itself runs out (a year from the date of issue) <- meaning EVEN with a re-entry permit you get stamped in only until the expiration date of your last entry

Keep in mind a re-entry permit (the one built IN to the visa) and one you would buy after the visa expires doesn't add any time to your actual entry stamp <- the stamp that lets you stay IN thailand. All it does is let you get back in

If you do it while the visa is valid you get stamped in for another year, if you do it AFTER the visa itself expires you get stamped back in until your previous entry stamp expiration?

The LONGEST stay you can get out of a year-long, multi-entry Non-OA visa is just about 2 years. <- That's IF you exit the country and re-enter just before the visa itself expires, you'd get a new year entry stamp. THEN you're done on that visa and when that year runs out you'd have to either go back to your country and buy a NEW OA visa or you'd meet the requirements (proof of funds and insurance) and get a yearly extension in country at the immigration office for 1900baht.

You can't get endless stays of a year at a time out of that visa, it's capped out after 2 if you work your dates right