If you have a Non-O visa based on marriage you only need “seasoned” 400,000 THB . When you file for the extension the immigration office will give you about a four week extension counted from the day you show up at the immigration office. Within the first two weeks of that extension period you will receive a visit from immigration who will then send your file to the HQ in Chaeng Wattana and you will pick up your extension at your local immigration office. Important: any re-entry stamps that you have on your original non-O visa become invalid once you receive the “under consideration” stamp so if you want to travel within those four weeks out of the country you need to get a new re-entry permit.