On 1 January 2019, the provisions introducing the obligation to provide the National Tax Administration with information on tax schemes (MDR) and additional obligations depending on the role an entity plays in relation to a particular scheme came into force. The application of the MDR provisions since their inception has given rise to a number of uncertainties, which have been affected by successive amendments. At the same time, failure to comply with the obligations imposed by the MDR provisions may result in severe sanctions.