What do I need for the 90-day check-in at immigration in Thailand?

For the 90-day check-in at Thai immigration, the required documents can vary by office. Generally, most responders mentioned needing the TM47 form and a passport. In some locations like Chiang Mai, the TM30 is also required, which has become a common necessity recently. It's advised to check the specific requirements of the local immigration office you plan to visit, as the needed documents can change.