Exactly. When I left my last job I got a slightly odd “ not approved” Extension of Stay stamp giving me 7 days to leave the country after submission of my WP cancellation receipt to immigration. I don’t recall what form I submitted to get the stamp as it was prepared by my employer HR manager but I remember paying the 1900 Baht.
I try to do the on line report 14 days prior to the due date as you mention because if it fails it leaves you plenty of time to schedule an in person report before the due date. You could also do a report by registered mail but the Immigration website suggests sending it 15 days prior to the due date and they recommend contacting immigration if you don’t get a reply within a month. Don’t forget to include a self addressed envelope with a stamp if you do this otherwise you will never get a reply!
I had a similar problem on my last arrival. I just did a 90 day report using the paper form ( due to the glitch in the online reporting system) and it wasn’t mentioned so I assume that it is ok. The importance of checking your passport for correct stamping after passing through immigration in any country can’t be overstated. Many years ago I passed through the land border between Nepal and India and the Indian IO stamped my passport with an exit stamp instead of an entry stamp. Fortunately I spotted it before leaving the office and got it corrected but I was questioned about that when I left India later. Never assume. Always check!
I am on an Elite visa (PE) and found in the past that when I put the visa expiry date into the online form my 90 day report was rejected. However if put the entry stamp expiry date it was approved. On Elite visa you get 1 year entry stamp when you arrive in Thailand even though the visa expiry is longer. I just thought I would mention this because the OP didn’t mention what visa he was on. You don’t put visa expiry date in the paper form so it isn’t an issue.
Is it worth pointing out that people who used to use the the old TM30 ( Section 38) app will have to apply for a new account as the login details used for the app won’t work?
Thank you. It is more convenient for me to keep the funds for the purpose of stay extension in one account and use piecemeal transfers to another account for living expenses rather than transferring 400k every year.