<p>The aim of this paper is to evaluate the long-term impact on Spanish individual income tax (IRPF) compliance of the amnesty measures granted in 1991 within the framework of the 1988-91 income tax reform programme. To that end, we combine time-series techniques with outlier detection methods and the Bai and Perron (1998) test for the endogenous estimation of structural breaks. On the basis of the analysis of the monthly IRPF tax collection series from 1979 to 1998, we find that the amnesty had no effect on tax collection in either the short or the long term. By contrast, we find evidence of the permanent positive impact caused by the legislative and administrative measures linked to the IRPF reform process begun in 1988. </p>