HM Revenue and Customs (HMRC) faces an increasing problem of older tax debts which are harder to collect, according to a spending watchdog.

The National Audit Office (NAO) said HMRC is facing increasing issues from debtors who do not engage with it.

Debt that was more than a year old and not covered by a payment plan increased from £5.3 billion before the coronavirus pandemic to £18.6 billion at the end of 2025-26, with cost-of-living pressures making it harder for some taxpayers to pay.

At the end of 2025-26, 8.2 million taxpayers were in debt to HMRC, with their tax debts totalling £43.8 billion, or 4.7% of total tax receipts.

This is down from 5.6% in 2022-23, the NAO said, with a peak of 9.3% having previously been recorded at the end of 2020-21, during the coronavirus pandemic, when HMRC paused its debt enforcement activities.

But the NAO’s report said: “The tax debt balance remains significantly higher than the pre-pandemic period: in the five years between 2015-16 and 2019-20, tax debt was…