Can I use my 90 Non-O visa if I return to the UK early, and how should I fill out the TDAC form?

The Visa or visa exempt crackdown. Has no impact at all on a non O visa, if you get a non O visa for your return you dont need onward travel at all since you have a long term visa. Don't worry either about the tdac you can put reason for visit as the most appropriate to you!!

The non O visa 90 day validity period is used up the moment you entered thailand and you got your 90 day stamp , you can't leave and return on that visa ans get another 90 days stamp as its used up/finished, other than what I have already said above about getting a re-entry permit.

Given your situation, you should be fine to use your 90-day Non-O visa, even though your plans changed and you're heading back to the UK earlier than expected.

When completing the TDAC form, you can still put "visiting family in Thailand" as the purpose of your visit, even though you're cutting your trip short. It's not necessary to change it to "Holiday" if that's not the primary reason.

Regarding the 90-day visa, it's not as restrictive as you might think. The 90 days refers to the visa's validity, not necessarily the amount of time you need to spend in Thailand. Since you've only used 58 days of your visa, you should be good to go.

As for the new immigration clampdown, it's unlikely you'll be flagged as suspicious, especially since this is your second visit this year and you've complied with the visa rules so far. Just make sure to have all your documents in order, including proof of onward travel and sufficient funds.

Before you head to the airport, double-check the TDAC requirements and ensure you've completed it correctly. You can also contact the Thai immigration authorities or your airline if you have any further questions. Safe travels!

You can get a re entry permit for your non O retirement visa before you leave to keep it valid But you will not get any additional time on your re entry stay you will only get stamped in for your original visa expiration date, so only a month left on your non O visa. The tdac it doesn't matter what you put as the reason for visit, holiday, thai family etc.

the Non–O E–Visa PDF File that you received from the Thai Embassy in London is Single Entry only, so once it has been used, then that's it....