The National Fiscal Service explains

In the event of illegal import of goods to the customs territory of Ukraine or their export, customs payments due are calculated at the rates set on the date of bringing the goods through the customs border of Ukraine, however, in case it is impossible to find the date, - on the date of ascertaining the fact of illegal import (export), the press-office of the National Fiscal Service reports.   

In case of loss, non-delivery or issuance of the goods without the permit of the authority dealing with revenue and duties to be paid for the goods that pass through the customs territory and are under the customs supervision, either transit or temporary stored, the customs duties are charged at the rates set on the date of accepting the goods to further move them or place into temporary storage. 

If it is impossible to determine the amount of customs duty payable as far as the actual data on nature of goods, name, quantity, country of origin, or customs value has not been given to the revenue and duties authority, the amount of charges are calculated using the maximum value of customs duty rates, a number or value of goods that can be confirmed on a basis of the data provided.

In case the products that have been conditionally exempted from taxes are not used as intended, or in case of breach of the customs regime the placement of goods under which implies conditional exemption from taxes, the customs duty rates applied are valid on the date of receipt of the customs declaration for clearance.

The relevant norm is set out in article 296 of the Tax Code of Ukraine dd. March 13, 2012, under No.4495-VI, as amended.