The European Union executive sent an invoice demanding that Poland pays up for failing to halt its disciplinary regime for judges despite it having been struck down by the bloc's top court as undercutting the law on judicial independence.
"The letter was sent," a spokesman for the European Commission, Christian Wiegand, said.
Sources have told Reuters earlier that the fines amount to around 70 million euros and that the Brussels-based Commission would give Warsaw some 45 days to pay.