My contract expires on Sept 30, day which I will leave the Kingdom. I have already extended my visa until the 30 upon presenting my contract and copy of the WP and current letter of employement.

My WP so far is valid until the 21 of Sept, in fact the next step should be to go and renew it. However, I am considering non extending it for the last remaining week, or else it's more the time I'd spend in the Thai immigration/labour and related offices than I'd spend at work. (not to mention that it's their fault that if you get a one year work contract they fail to issue a one year work permit, they always break it into two pieces, "stopping" first at the date you entered the country the first time).

When I do leave on Sept 30, would they ask for my WP? Can they (I am sure they can, but do they usually?) cross-check I renewed it?

Also, what am I supposed to do with my WP? Return it? Can I mail it in once I left Thailand, saying "sorry I forgot"?

And finally, should one day (not likely within the next 2 years) come back and work in TH, would I have troubles for not having followed the "correct" protocol (provided there is one)?

Any advice apreciated. Thanks.

Since you have the contract and the visa extensding the work permit until the 30th should be a routine matter.

Won't your employer deal with this?

I expect your employer will appreciate it if you do return the work permit when you leave,

otherwise they may have trouble next time.

No one will ask for the permit at the airport.

Thanks. My employer is a university, they don't seem to care much nor be very helpful. It's me who has to go to all offices (alone) bring all docs and pay all fees. I will check with them whether they need the WP back.