The Distributional Effects of Tax‐benefit Policies under New Labour: A Decomposition Approach*

I revisit the distributional effects of tax‐benefit policy reforms under New Labour using counterfactual microsimulations embedded in a Shapley decomposition of time change in inequality and poverty indices. This makes it possible to quantify the relative effect of policy changes compared to all other changes, and to check the sensitivity of this policy effect to the use of (i) income vs. price indexation, and (ii) base vs. end period data. Inequality and poverty depth would have increased, and the sharp fall in child poverty would not have occurred, had the reforms of income support and tax credits not been implemented.