IFS Briefing Notes (BN72)

Options for a UK 'flat tax': some simple simulations

Date: 11 August 2006
Authors: Stuart Adam and James Browne
Volume, issue, pages: 22 pp.
DOI: 10.1920/bn.ifs.2006.0072
This Briefing Note analyses the effects of four possible flat tax systems for the UK: one that flattens the rate structure of income tax only, one that also flattens National Insurance contributions, and two that flatten the combined rate structure of income tax and tax credits (with and without flattening National Insurance contributions as well).

In all cases, the tax base is left unchanged. The analysis is conducted for the working-age population only, and in all cases the reforms are designed to be revenue neutral under the strong assumption that people do not change their behaviour in response to the reforms. We examine the effects of the reforms on particular example families and on the overall distributions of income and work incentives.