When can I apply for a 30-day extension on a single entry tourist visa in Thailand?

You can apply for a 30-day extension on a single entry tourist visa at local immigration offices in Thailand. In places like Jomtien Pattaya, it's recommended to apply within 7 days of your ending permission to stay date. While locations like Chiang Mai and Bangkok allow applications when there are 45 days or less remaining on your current stamp, other regions may require applications to be made within 30 days of the expiration. It's best to check with your specific local immigration office for their rules.