Some may know. Went to cancel my Work Permit today and was told new rule only employer can cancel. Rule verified by supervisor. Asked if ok to just leave WP expire she said employer still has to cancel. Believe they want employer to show taxes have been paid.
TLDR : Answer Summary
A recent change in Thailand's immigration rules states that only the employer can cancel a Work Permit. This change was confirmed by a supervisor at the office, and it seems that the government expects employers to prove that taxes related to the worker have been paid. If a worker wants to cancel their Work Permit, they need their employer or representative to accompany them to the office.