This is probably a simple one to answer, but I'd still like the opinion of those with more experience.

I have a normal 30 day visa. This expires on the 13th of this month. My flight out is for the early hours of the 22nd. So that's effectively 8 days, as I will pass through immigration on 21st. So, if I get a one week extension will I then be ok to pay a one day overstay at the airport? I am even thinking I may get the one day free, which is what I think happens.

Thanks.

No such thing as a 30 day Visa. You must have a 30 day Visa Exempt. As far as I know Immigration will only issue a 7 day extension if you can show a ticket leaving Thailand within those 7 days. Which you cannot.

You can try but I think you will need a border run.

You could give it a try as don't believe they always check outbound tickets - but a border run for 15 days would be the sure thing.

I have just returned from the local immigration office. I explained the situation to them and they gave me a one week extension and assured my I would be ok to pay for the over stay, which it turns out will only be one day. I don't like to pay the extra 1900baht but it beats doing a border run.

Thanks for the advice.

The 1900 baht is also better than a 4000 baht overstay fine.

You won't be charged for the 1 day overstay but you will get a little blue stamp that states (in Thai) that you overstayed less than 24 hours.