In February 2019, the CNMC published a study on public procurement procedures in Spain. Public procurement is very important in Spain: Depending on the estimate and the year, it accounts for 10% to 20% of Spanish GDP. This study evaluates the impact of implementing more competitive procurement procedures on economic efficiency. Specifically, the aim is to isolate and quantitatively determine the effect of the procurement procedure chosen on the cost of the contract for the government. Focusing of general government procurement data, the results of the econometric analysis performed show that the choice of the procurement procedure is not neutral in terms of the efficiency of public procurement. Specifically, the government pays, on average, 9.9% less in contracts for which an open procedure is used rather than a non-open procedure (negotiated, restricted and competitive dialogue). To illustrate the importance of this result, if it had been possible to use open procedures in all tendering, the cost of public procurement would have been – as a minimum and using very conservative criteria – some 1.7 billion euros less for the 2012–2016 period.