I want to know what a surcharge is

The procedure for the recovery of a debt evolves through different stages. The first is known as the voluntary payment period and the second as the enforcement period. The first begins with the notification of the corresponding debt, which opens the period for payment in the voluntary period, and the second begins if the debt is not paid in the corresponding voluntary period or if it is paid after the expiry of this period.

The payment terms in the voluntary period are established in article 62 LGT .

The enforcement procedure is that which is initiated by issuing an administrative act called an order for enforcement, and which is notified to the debtor when the debts have not been paid within the deadlines established in the voluntary payment period or have been paid after this period has expired. Therefore, if you have received a notice of an order for enforcement it will be a consequence of the debt not having been paid within the voluntary period and you will have to pay the debt together with a surcharge if the debt has not been paid or a surcharge if the debt has been paid after the end of the voluntary period.