Hi, I just wanted some clarification regarding the long stay "O-A" Visa. I have read that you can come and go as much as you like during the one-year validity of your visa, however from my consulate here in Canada it says a re-entry permit is needed or your visa will be considered void.
This taken directly from the site.
Recommendations for Foreigners with Non-Immigrant Visa "O-A" (Long Stay) While Staying in the Kingdom
Upon arrival, holder of this type of visa will be permitted to stay in Thailand for 1 year from the date of first entry. During the one year period, if he or she wishes to leave and re-enter the country, he or she is required to apply at the Immigration Office for re-entry permit (single or multiple) before departure. In the case of leaving the country without a re-entry permit, the permit to stay for 1 year shall be considered void".