8,12,1,1. General ideas

Errors or omissions in declarations already filed that have led to a payment being made less than that which was originally due or the receipt of a refund that is higher than that which was originally due, must be settled by filing a tax return complementary to the settlement filed.

Additionally, situations or circumstances that result in the loss of the right to a reduction or exemption already applied in a previous declaration must be regularised by filing supplementary tax returns.

However, the loss of the right to certain deductions must be adjusted in the tax return in which any of the requirements for the consolidation of the right to these deductions have been breached.