The situation stems from Royal Decree 1039/2022, which modified IRPF (Income Tax) regulations to lower monthly payroll withholdings starting in January 2023. While this provided more monthly take-home pay, it often resulted in underpayment of the total annual tax due.

Financial experts estimate that affected individuals could face adjustments ranging from 400 to 900 euros. The impact varies based on family circumstances and the exact salary level, with those closer to the 22,000 euro mark being the most affected by these discrepancies.