35 years of reforms: A panel analysis of the incidence of, and employee and employer responses to, social security contributions in the UK

We examine the effects of employee and employer social security contributions (SSCs) on labor cost, hours of work, and labor cost per hour, using a long running panel dataset that allows us to exploit 35 years of policy reforms in the United Kingdom. We find that reductions in marginal rates of employee - but not employer - SSCs have positive effects on labor cost that operate through hours of work, while labor cost falls much more when average employer SSCs rates are reduced than when average employee SSCs rates are reduced, with most of this differential effect coming through reductions in hourly labor cost. We interpret this as evidence that employees change their hours in response to SSCs, but that in the short- to medium-run at least, the formal incidence of SSCs can matter for their behavioral impacts and economic incidence. (C) 2018 Institute for Fiscal Studies. Published by Elsevier B.V.