HMRC has already collected more than £137 million in late payment interest for the 2023/24 tax year, according to a Freedom of Information request by investment platform AJ Bell.
So far, around 1.3 million taxpayers have been charged interest for paying their tax late, with the average bill coming in at just over £100.
However, this figure is likely only part of the story. The data only includes cases where the interest or penalty has already been paid — meaning the final total for 2023/24 is expected to climb significantly.
A look at last year’s figures highlights this trend. For 2022/23, the total amount collected has surged by more than 30% over the past year, now sitting at just over £200 million.
One key driver behind the rising sums is the increase in HMRC’s late payment interest rate. From April 2025, the rate was raised to 4% above the Bank of England base rate, making missed deadlines more expensive than ever.
Charlene Young, Senior Pensions and Savings Expert at AJ Bell, said the figures reflect a broader issue:
“These latest figures suggest that taxpayers still face difficulty navigating the UK’s complex tax system — and HMRC are cashing in as a result.
Millions have paid late payment interest in recent years, despite efforts to simplify who needs to file a self-assessment return.
It’s easy for taxpayers to get caught out by confusing systems and deadlines, and mistakes or delays can quickly lead to higher interest and penalties.”
With costs rising and rules still proving tricky to navigate, staying on top of deadlines has never been more important for UK taxpayers.
