I see that my Non O visa is valid for 12 months, Ive read that if I do a visa run just befoere this expires I can get another 3 months in the country on expired visa. I have another 6 months left but I'm already starting to feel the visa HeadF*ck coming along! haha.

Thank you.

Do a border run a day or two before it expires and you will get another 90 days.

This is assuming that it is a Visa and not an extension of stay.

Do you have a multiple entry O visa, the kind that you have to leave the country every 90 days?

If yes, then by leaving just before the 'expire' date, you'll get another 90 days, giving you almost 15 months.

If no - because it's a one year extension, then the answer is No.

Yes its a 12 month mulitple O Visa - then after the 15 months I would like to change to a B and get a work permit, I guess I will have to go somewhere like the U.K or Singapore for that.

Thank you for the replies

You get a work permit in Thailand and you can do that on a non immigrant O visa. But you need employment.