I'm coming to the end of my marriage visa multi entry 12 m,I will go the trip to savvanahket to renew, I've heard you can get extra months this visa, what's the situation ?definitely heard 15m.
TLDR : Answer Summary
You can extend your marriage-based Non-Immigrant O visa in Thailand to potentially gain up to 17 months total. By doing a border run to Savannakhet before your current visa expires, you can receive an additional 90 days, effectively totaling 15 months. Additionally, if you visit an immigration office before the 15 months end, you can apply for a 60-day extension based on your marriage, for a fee of 1,900 THB, which allows you to stay for nearly 17 months. Alternatively, you can also consider applying for a one-year extension directly at your local immigration office without needing a border run.