OTS launches tool to measure UK tax complexity

THE OFFICE OF TAX SIMPLIFICATION has finalised its complexity index, a spreadsheet tool for analysing and measuring the relative complexity of the UK tax system.

The OTS, headed by John Whiting (pictured), will use it to identify future projects and for monitoring changes in complexity in different areas of tax.

The spreadsheet divides the tax system into 107 discrete areas, then assigns to each area values for ten different complexity factors, six for “intrinsic complexity” and four for “impact of complexity”.

Combining those factors using roughly equal weightings creates two numbers between one and ten for the relative complexity of the tax area: one for intrinsic complexity and one for impact of complexity. Ten is the most complex, one the simplest. The spreadsheet can then be sorted by these numbers in descending order to find the most complex areas of the UK tax system.

The values for the complexity factors have been provisionally filled in by combining the professional judgments of five OTS staff. As this group does not have experience of every single part of the tax system, the body harbours concerns some of the values may be inaccurate and proposes to ask a wider group of people to fill in the spreadsheet over the next few months.

The OTS’ future was secured when the Conservatives gained power, with financial secretary to the Treasury David Gauke announcing that it would have an expanded remit and greater resources.  

If you are interested in contributing, e-mail the OTS team at

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