GOV.UK has published details of the most recent measurement of the tax gap for 2022-20223.
What is the tax gap?
The tax gap is measured by comparing the net tax total theoretical liability with tax actually paid. This is comparing the amount of tax HMRC expected to receive in the UK and the amount HMRC actually received.
The figures
The tax gap is estimated to be 4.8% of total theoretical tax liabilities, or £39.8 billion in absolute terms, in the 2022 to 2023 tax year.
Total theoretical tax liabilities for the year were £823.8 billion.
There has been a long-term reduction in the tax gap as a proportion of theoretical liabilities: the tax gap reduced from 7.4% in the tax year 2005 to 2006 to 4.8% in the tax year 2022 to 2023.
While most of the components follow a downward trend, with the largest proportionate fall between 2005 to 2006 and 2022 to 2023 in the VAT gap, falling from 13.7% to 4.9%, the Corporation Tax gap estimate has increased from 11.4% in 2005 to 2006 to 13.9% in 2022 to 2023.
The Corporation Tax gap share has increased from 17% of the overall tax gap in 2018 to 2019 to 34% in 2022 to 2023, while the share of the tax gap from VAT has fallen from 28% of the overall tax gap in 2018 to 2019 to 20% in 2022 to 2023. The Income Tax, NICs and Capital Gains Tax gap share decreased from 39% to 34% over the last 5 years.
The tax gap from small businesses is the largest component of the tax gap by customer group at a 60% share in 2022 to 2023; the tax gap from wealthy and individuals each make up a low proportion of the tax gap at 5% each in 2022 to 2023
The VAT gap
VAT represents 20% of the overall tax gap.
The VAT tax gap is 4.9%.
There are several approaches to measuring tax gaps. VAT and excise duties gaps are mainly estimated using a ‘top-down’ approach, by comparing the implied tax due from consumer expenditure data with tax receipts. Most other components are estimated using a ‘bottom-up’ approach, based on HMRC’s operational data and management information.
A top-down approach uses independent, external data on consumption to estimate the tax base. The tax base is used to calculate a theoretical value of tax that should be paid. The actual amount of tax paid is subtracted from this theoretical value to estimate the tax gap.