I am arriving in Thailand Friday 13th September and departing Sunday 13th October. I know you can stay 30 days however my stay means im there for 31 days. I arrive about 7pm, could I wait until after midnight to go through passport control so my stamp is then 14th September making it 30 days or is the date stamp when your flight arrives on the 13th. Hope I have made myself clear. Many thanks

Your biggest concern would be that you might be refused to board your flight without a visa or ticket out within 30 days.
Suggest you get a tourist visa before you come.

Your biggest concern would be that you might be refused to board your flight without a visa or ticket out within 30 days.

Suggest you get a tourist visa before you come.

The OP appears to have a firm departure date of 13 October, which leads me to suspect that he/she has already booked a return flight ticket. However, I certainly agree that a 60-day tourist visa does seem to be the most practical solution in this instance.

Since the OP will need to enter his/her flight number in his/her completed TM6 arrival card, the Immigration Officer whom he/she encounters st Suvarnabhumi may well have some hi-tech means of checking that his/her flight actually landed on 13 September - even if he/she were to delay this auspicious encounter until after midnight - and stamp his/her passport on this basis.

Just arrive normally and when you go to leave you may have to pay a 1 day overstay which is 500baht. Thats it!

This is such a common occurrence that the Thai immigration overlook a 1 day overstay, many people for example catch the 1am flight on the day after thier permission to stay expires.. Its not a big deal..

The immigration will not penalise you for a one day overstay! You will fly through as if nothing has happened.

Something I should of said is I already have a one day overstay stamp on my passport, so they may not be too happy with me doing it again. I know it would be wise to get a visa extension but its just one day and trying to avoid paying more money.

it is a non-issue. including your existing overstay stamp

it is a non-issue. including your existing overstay stamp

+1, don't worry! you are not taking the P***