The request for postponing or tax debts paying in instalments means the taxpayer must pay interest on arrears, regardless of whether the administration agreed to grant or deny the request. In this sense, it is necessary to distinguish the following situations:
a) Postponement is granted. Interest on arrears is calculated on the postponed debt, by the time between the expiration of the period of voluntary payment and the time period granted.
b) Fractionation is granted. Interest is calculated on each fractional debt, the period between the expiry of the voluntary payment period and each time period granted.
In both cases, if the requested postponement or fractionation is during the executive period, the basis of calculation of interest does not include the surcharge of urgency.
c) The postponement or fractionation is denied. Interest shall be calculated on the entire debt, for the time between the expiration of the voluntary payment period and the date of the negative decision.
Obviously, if the Administration resolves the request before expiry of the voluntary payment period, there is no interest on arrears for delay.
If the request for deferment or instalment was made in the executive period, the interest is settled by Administration, once the surcharge debt is paid, for the time elapsed from the expiry of the voluntary payment period, without calculating the surcharge payment.