HMRC urges traders to prepare for end of Brexit transition period HMRC is urging traders to act now to avoid Brexit-related disruption when the transition period comes to an end. Some 250,000 letters and emails have been sent to businesses warning that new border controls will come into force on 1 January 2021. HMRC’s Katherine Green and Sophie Dean said: “We understand that these are challenging times, but time is running out for businesses to get ready. “New customs and tax rules will not change or go away if a Free Trade Agreement is negotiated, so businesses should act now to ensure they are ready for the end of the transition period.” Meanwhile, the National Audit Office has warned that preparations for new border controls have been further delayed by coronavirus, likely leading to “widespread” disruption at ports.