Once you have all the paperwork complete you need to visit the district office which is similar to a town hall or registry office. In Thailand it is known as the 'amphur' (called 'khet' in Bangkok). For the marriage to be valid under Thai law it must be registered at the amphur office. A religious ceremony on its own is not recognized as being valid under Thai law. Please be aware that you are officially married on the day that you register at the amphur office.