Self-reporting of customs violations in Thailand is normally carried out at the ports. However, in 2020, the Customs Department launched a campaign called the One Stop Service Program (OSSP) for business operators to self-report issues relating to unpaid customs duty from a central location in Bangkok. The current extension of the OSSP, which has been extended several times over the past few years, is due to expire on September 30, 2026, although a further extension seems likely.
Source: tilleke.com
