HMRC missed out on £46.8bn in tax last year. Small businesses and Corporation Tax make up the biggest share of the shortfall.

The tax gap for the 2023-24 tax year has been published and is estimated to be 5.3% of total theoretical tax liabilities.

The tax gap is basically the difference between the amount of tax that should have been paid to HMRC and the amount of tax collected by the Exchequer. The gap includes tax that has been avoided in the UK’s black economy, by criminal activities, through tax avoidance and evasion. However, it also includes simple errors made by taxpayers in calculating the tax they owe as well as outstanding tax due from businesses that have become insolvent. 

In monetary terms, the tax gap is equivalent to lost tax of £46.8 billion. This means that HMRC collected £829.2 billion or 94.7% of all tax due.

The government has announced plans to raise a further £7.5 billion through its measures to close the tax gap.

Some of the key findings from this year’s calculations show:

• Small businesses represent the largest proportion of the tax gap (60%).
• Corporation Tax accounts for 40% of the total tax gap.
• Failure to take reasonable care (31%), error (15%) and evasion (14%) are among the main behavioural reasons for the overall tax gap.

As announced at Spending Review 2025, £1.7 billion will be provided to HMRC over four years to fund an additional 5,500 compliance and 2,400 debt management staff in order to try and ensure that more of the tax due is paid, to fund public services.