Tax complexity

A project exploring why tax is complex and how to measure complexity

Since it was set up in 2010, the Office of Tax Simplification has been carrying out an ongoing project looking at the reasons why tax is complex. In our first five years, we published a number of papers on the subject, available here

These papers include

  • an analysis of the length of tax legislation, concluding there were effectively 6,102 pages of primary tax legislation in 2011
  • a review of all 639 numerical thresholds in tax legislation in 2012
  • several papers setting out how we were developing a “complexity index”, a tool to measure the relative complexity of different parts of the tax system

In June 2015 we published a paper setting out the lessons we have learnt about tax complexity so far, summarised in four principles for avoiding complexity:

  1. Ensure the proposed tax measure meets the policy aims
  2. Focus the measure carefully
  3. Design the measure to meet the aim
  4. Maintain the measure properly

Alongside these principles, we published a final version of our complexity index in the form of a spreadsheet, giving relative complexity scores for over 100 different parts of the UK tax system.

We plan to continue our complexity project in the new parliament, exploring other aspects of tax complexity including the link between tax avoidance and complexity, a look at drafting style and the way new technology could be used to reduce administrative complexity.

Recent documents

  1. How to avoid complexity in the tax system
  2. Office of Tax Simplification complexity index

Publications in the project 2010 - 2014

  1. OTS complexity index methodology
  2. Developing a tax complexity index for the UK
  3. Definitions in tax legislation and their contribution to complexity
  4. Definitions in tax legislation and their contribution to complexity
  5. Tax thresholds
  6. List of tax thresholds
  7. Length of legislation
Published 18 June 2015