Viewpoint: Empirical evidence and tax policy design: lessons from the Mirrlees Review

This paper examines the role of evidence in drawing up the recommendations for tax reform in the Mirrlees Review. The arguments are organised loosely under five related headings: (i) Key margins of adjustment. (ii) Measurement of effective tax rates. (iii) The importance of information and complexity. (iv) Evidence on the size of responses. (v) Implications from theory for tax design. Although the Mirrlees Review focuses on all aspects of tax reform, the focus is this paper is on the taxation of earnings with some examples drawn from the taxation of consumption and savings.