DP2172 | Does Tax Smoothing Imply Smooth Taxes?


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Using a stochastic growth model we derive analytic expressions for optimal labour and capital tax rates under both complete and incomplete markets. We find taxes are driven by two factors reflecting : (a) Ramsey efficiency considerations and (b) the financing needs of the government which vary with the excess burden of taxation. In the case of complete markets the government insures against variations in the excess burden of taxation and taxes change purely for efficiency reasons. The serial correlation and volatility of labour taxes are determined by those of employment and do not necessarily imply smooth tax rates. Under incomplete markets both Ramsey considerations and variations in the excess burden of taxation lead to changes in taxes with the latter providing a unit root component to optimal labour taxes. Using US data we find that the majority of fluctuations in marginal tax rates are due to fluctuations in the excess burden of taxation rather than exploitation of Ramsey considerations.