I got my 1-Year Multiple Non-O visa at around mid-October last year. But I didn't enter Thailand with this visa until late-November last year.

So do I have to re-enter Thailand by mid-October or late-November of this year in order to take advantage of getting another 3-month stamp to make it a 15-month stay?

when the thai visa gurus come online they will tell the correct answer,but in the meantime i would think you would have to re enter the last time before the expiry date on your visa to obtain the extra 3 months,i dont think the 12 months of your visa begin on your first entry date.

when the thai visa gurus come online they will tell the correct answer,but in the meantime i would think you would have to re enter the last time before the expiry date on your visa to obtain the extra 3 months,i dont think the 12 months of your visa begin on your first entry date.

Yes, thats correct. You have to re-enter before your visa expires. The 12 months begin when the visa is issued, not when it is first used.

Edited September 11, 200916 yr by mxyzptlk

Yup ^^^

The visa has an 'enter before' date, you must enter BEFORE that date, if you try to use the visa actually on the enter before date you will be likely denied your final 90 days