What do I need to extend my TR visa by 30 days in Thailand?

To extend your TR visa for an additional 30 days, you'll need to fill out the Tm.7 form, which you can obtain at the immigration office. It's advisable to submit your application before your 60 days expire, as applying early does not affect your remaining days on the visa. Make sure to check what other documents may be required based on your current location in Thailand.