Can I extend a tourist visa in Thailand?
Many visitors can apply for an extension before their permitted stay expires, but eligibility, documents and timing depend on their entry type and current rules.
Overview
Tourist visa and tourist-entry extensions are normally handled at a Thai Immigration Office inside Thailand. The important thing is to check the permitted-until date stamped in your passport and apply before that date, not after it. You may need your passport, application form, photo, address information, copies of passport pages, proof of stay, fee payment and any extra documents requested by the local office. Rules and local practice can vary, so it is sensible to check the relevant immigration office requirements before attending. Do not assume your airline ticket, visa sticker or original plan overrides the date stamped by immigration on arrival.