Getting a new passport and being busy made me realize I overstayed my "B" visa for 40 days. I need a new immigration stamp to new my passport.I am planning to leave the country anyways in 30 days. What is best approach? Stay for next last 30 days - say that my old passport is stolen - and hope they wont jail me as I depart through airport. And pay the fine as I leave the country?All help appreciated - thanks!

Probably best in the visas section.

You are on overstay and will need to pay the fine of 20,000. Normally you can just do this when you leave Thailand at the airport and will only have a small delay.

But 30 days from now is a long time. If immigration/police checks you in the street and spots you have an overstay they can arrrest you and detain you till you have paid the fine and have a ticket out of the country. Immigration for example checks hotel registers.

If you want to sort it now, just buy a ticket out of Thailand and go to the airport, pay the fine, leave and return the same day if you want.