Just landed and am in my taxi to Soi 11.
I never installed the app. I just did my TDAC as usual. And as usual they never asked to see it anyway. THIM definitely not mandatory yet, but I still don’t know about TRIM, haha

Thanks everyone for the information as I'd not heard of this. Have installed the app, registered, scanned my passport and done the facial recognition so all I need to do now is add my trip 72 hours before to get the QR code.

Sorry one point of clarification. You do your arrival card within the app, but the app I also does other immigration services and not just the TDAC. For a regular visitor it’s worth using the app just so you can save your passport details in your profile making it easier to fill out your arrival card.

This hasn't become law yet (August 11, 2026) as far as I can tell.  It has to become published in the Royal Gazette first.  I have read, (but am not sure), that the old rules stay in effect until 15 days AFTER it gets published. @Johan S If you have a US passport the Visa on Arrival does not apply to you. 

@CanadaVisitor - they are the same thing. One is a webform and one is an app. You’d get a QR code and your trip will be registered with immigration whichever option you choose.