Recently, the Customs Department re-interpreted section 19 of the Customs Act by claiming that customs officers have the power to assess duty on shipments imported within the previous three years, and the period for assessing duty can be extended further, up to two years back, and then another five years back, leading to an assessment of duty for up to ten years as from the date the import declaration form was submitted.
The Customs Act, B.E. 2560 (2017) ("Customs Act") became effective on 13 November 2017, and provides a limited period for customs officers to assess additional duty from importers who fail to make full payment of duty and tax. It is common for this period to lapse, after which the customs officers no longer have the power to assess duty. This regulation benefits importers who import goods that are no longer subject to duty assessment because the period for duty assessment has expired.
The period for conducting duty assessments is prescribed in section 19 of the Customs Act, in the second and third paragraphs:
Second paragraph: "The assessment of duties under paragraph one shall be conducted within three years as from the date of submission of an entry form except that in the case of necessity preventing the conduct of assessment of duties within such time, a request shall be made to the director-general for extension of such time for a period not exceeding two years."
Third paragraph: "In the case where there appears evidence to the satisfaction of the director-general that the person liable to pay duties has the intent to defraud on duties, the customs official shall have the power to conduct further assessment of duties within five years as from the expiration of the period of time under paragraph two."
Historically, at the time of drafting the Customs Act, the Ad Hoc Committee on the Customs Bill interpreted this extension as a mere extension of time in which to submit paperwork. Whether or not this extension is granted, a customs officer could assess duty on shipments imported for no more than three years before this initial period ended.