In yesterday’s Spring Budget, HMRC was given an extra £140 million in funding for its debt management capability, which is projected to bring in an extra £4.3 billion in unpaid tax by March 2029.

HMRC data shows that delinquent tax debts – those not agreed with HMRC – stood at £39.1 billion at the end of 2023.

Steven Porter, partner and head of tax disputes and investigations at international law firm Pinsent Masons,...