i am currently on a valid non-imm b visa which started in august 2011, around august 12th or so. i have to leave thailand next week for a couple of weeks, am i right in thinking that when i return to thailand around august 2nd or 3rd or so i can still obtain a further 90 days' stay on this current b visa?

if this is correct, this would in theory take me up to the start of november on this b visa. i then also need to make a trip out of thailand in mid-september for a week - how would this be valid? would i need to request a re-entry permit on this current visa?

A visa only allows a 90 day stay so need to know what you actually have. If you have a multi entry visa the valid until date on the visa itself is key (no entry after that date - any entry before that date a 90 day stay). When it was first used has nothing to do with it. It is valid for one year from date of issue.

ah yes, you're quite right. it's a multiple entry non-imm b and is valid until august 17 2012. so if i come back into thailand on august 2nd or so i will receive the additional 90 days' stay on that visa? and what then if i want to exit for a week in september and come back in on the same one?

After your visa expires you will need a new visa to get a new 90 day entry.

You could get a re-entry permit from immigration that would keep your last entry valid as long as your permit to stay is still valid.

thanks both. does that mean that i'll be able to come back in on the current visa and then leave in september and come back in on a re-entry permit? need to know this for september.

Yes but the September entry will only give you the remainder of your 90 day stay that started in August so likely be early November you would have to leave.

You will get 90 days from the date of your arrival, if the visa is still valid as you wrote. If you leave the country, that 90 days also expire. You should get an Extension of Stay before that happens.

Poster is not asking about extension of stay (suspect it is not an option) - for what he asks a re-entry permit is what is required.

Yes but the September entry will only give you the remainder of your 90 day stay that started in August so likely be early November you would have to leave.

ah i think that clears it up then. thanks for the help lopburi.