Research and analysis

Office of Tax Simplification complexity index

A spreadsheet for measuring the relative complexity of parts of the UK tax system.

Documents

OTS Complexity Index June 2015

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OTS complexity index methodology June 2015

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Details

The Office of Tax Simplification (OTS) has finalised its complexity index, a spreadsheet tool for analysing and measuring the relative complexity of the UK tax system. It will be used by the OTS 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. It then assigns to each area values for ten different complexity factors, six for “intrinsic complexity” and four for “impact of complexity”. Combining these factors using roughly equal weightings creates two numbers between 1 and 10 for the relative complexity of the tax area: one for intrinsic complexity and one for impact of complexity. 10 is the most complex, 1 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, some of the values may be inaccurate. We propose to ask a wider group of people to fill in the spreadsheet over the next few months. If you are interested in contributing, or if you have any comments or questions, please email the OTS team at ots@ots.gsi.gov.uk.

Published 18 June 2015
Last updated 3 July 2015 + full page history
  1. We have updated the methodology paper explaining how the index works, and corrected some minor errors in the original spreadsheet.
  2. First published.