On what value of the goods will the Transaction Tax be calculated under the 2026 UK/EU Treaty for Gibraltar?

Short answer

For imported goods, the taxable amount is based on the customs value, including taxes, duties, levies and incidental expenses like commission, packing, transport and insurance. For goods produced in Gibraltar, the taxable amount is the open market value at the time goods leave the production site - the full amount a customer would pay under fair competition conditions.