Portugal’s Tax Authority reminded that the Vehicle Circulation Tax must be paid by the last day of the vehicle’s registration month
One source
What the source said
Notícias ao Minuto
“O Imposto Único de Circulação (IUC) "está a pagamento até ao último dia do mês da matrícula do veículo”
Machine translation: The Vehicle Circulation Tax (IUC) "is payable until the last day of the vehicle’s registration month"
Read at Notícias ao MinutoReported by one source so far. It is confirmed when a second, independent source reports the same thing.