Although specific rules were introduced in 2004 for the funding of political parties at the European level, the EU institutions have traditionally refrained from regulating political finance and electoral campaigns. Instead, this has largely remained the preserve of member states, which have very different political traditions and diverging regulatory regimes for campaign and party finances, including the digital and online aspects. Since 2019, the EU has started to take several regulatory steps to confine campaigning, particularly in the digital sphere. This case study examines the implications of these new EU rules for political finance, with a specific focus on online advertising.