Can I travel to Singapore and return on a non-O Tourist visa without voiding my extension eligibility?

@Eric *****

then you do not have a tourist visa. You have a 90 day non-visa based on retirement.

You cannot get a 30 day extension. The only extension you can get from this visa is the 1-year retirement extension by showing 800,000 baht in your Thai bank account and it must be there for 2 months already by the time you apply for the extension.

If you do not plan on applying for the 1-year extension or cannot apply for it, then you have 2 options:

1) Your current entry stamp should end sometime in November if you entered in August. When you leave you can apply for a re-entry permit and when you return you will receive the same permission to stay as when you left which will end the same date in November as before.

2) leave without a re-entry permit, thereby forfeiting your visa and your ability to apply for a retirement extension. Then when you return you'll be stamped in for 60 days visa exempt, which is eligible for one 30-day extension.