IMI is paid annually using a single collection document (DUC).
It must be paid in the month of April; for amounts exceeding €250, it is paid in two instalments in April and September.
Single collection documents issued outside of the normal settlement time are paid before the end of the month following that of notification.
The central services of the Portuguese tax authorities send a notification letter for payment to the tax address of each taxpayer residing in Portugal before the end of the month preceding that of payment, except for collection documents involving settlements outside of the time period. These follow by registered letter.
Any taxpayer who does not receive a payment document may request a second copy from any tax office.