In this contribution the author examines how, from a customs perspective, the integrity of the internal market is protected after the transitional phase under the Revised Protocol on Ireland/Northern Ireland. He briefly discusses the customs aspects of the Withdrawal Agreement and then examines in depth the revised arrangement with regard to the Irish border in light of the protection of the integrity of the internal market. He shows that the revised arrangement cleared the Brexit deal through parliament and paved the UK’s way to leave the EU on 31 January 2020. He concludes, however, that given the complexity of the legislation underlying the revised arrangement, the UK will be paying a high price for getting Brexit done, keeping the Irish border open and protecting the integrity of the internal market of the EU.