The issues of tax compliance and efficiency of tax administrations have gained widespread attention among scholars and policymakers in the aftermath of the global financial crisis. One of the prominent examples of tax compliance crises in Europe was the Polish VAT gap that was widening over the 2011–2014 period. Although post-crisis recessions in various countries can explain a lot of cross-country variation in tax compliance, the experience of Poland seems unique. Despite uninterrupted economic growth, the size of Poland’s VAT gap approached the Greek levels. In other words, the Polish VAT-compliance crisis could not be downplayed as a simple consequence of the downturn; instead, performance of the tax administration seems to be the key factor. Unfortunately, secrecy surrounding tax administrations’ activities substantially limits the scope of scientific inquiry into their effectiveness. To overcome this problem, this article introduces a new source of information about their activities – a fulltext database of administrative court verdicts (concerning challenged decisions of the tax administration). A collected sample of 68.2 thousand VAT-related judgments provided an ‘opportunity sample’ containing information on the procedures of tax authorities, in particular the time elapsed from the underlying economic activity to the issuance of the challenged decision. Results indicate that such a lag averages almost five years. Given the evidence presented in this article, the incentive structure faced by the Polish tax authorities requires further rigorous scrutiny and – perhaps – a reform.