Can a non-immigrant visa in Thailand be extended through border runs or at immigration?

A non-immigrant visa in Thailand may not be extended by a border run; exiting the country typically invalidates the visa unless a reentry permit is obtained. Extensions can be applied for at local Immigration offices, provided the applicant meets specific requirements. A 30-day extension can be granted for a fee, requiring basic documents such as passport copies and hotel addresses. Depending on the situation, longer extensions (e.g., for retirement or dependents) may also be available.