Hi. I have a Non-Immigrant, Category O-A, Number of entries M, which says enter before 12 june 2015. I have been now in Thailand for over 6 months and doing my 90 day reports. I am planning a trip back to Europe and returning on the 8 june 2015. Does this mean that they will stamp my passport on arrival allowing me to stay one more year until 13 june 2016, and all I need to do is continue my 90 day reporting?

When you enter the country on June 8th you will get a one year entry.

After that you will need to get a re-entry permit at immigration to keep that one year permit to stay valid if you want to travel.

Just keep doing your 90 day reports.

Then prior to June 8th, 2016 you will need to get an extension of stay or a new visa.

Does this mean that they will stamp my passport on arrival allowing me to stay one more year until 13 june 2016, and all I need to do is continue my 90 day reporting?

You would get a one year permission to stay from the day you enter the country, not a year added onto the visa expiration.

You MUST have a re-entry permit for the "extra" year if you want to travel out and back in the country since you then only have a permission to stay and no visa. Contrary to what some people think, your visa is not extended a year, just your permission to remain legally inside Thailand.

Edited January 27, 201511 yr by Suradit69

OK. Thankyou both very kindly for your help.