Margen
Look at your last income tax return. If it came out at 600 euros to be refunded, that money was yours from day one: the State held it for twelve to eighteen months and paid you not a cent of interest for the privilege.
It is not a reward for good behaviour, nor a present from June. It is the difference between what was withheld from your payslip month after month and what you actually owed. Too much withheld now, a refund later.
Three steps, and they take under five minutes:
1. Take the amount you were refunded last year and divide it by twelve. That is what you were lending the State every month without noticing: 600 euros is 50 euros a month, twelve months running. 2. Check whether your withholding declaration is out of date. It is the form you handed your employer with your personal circumstances, and it is what sets your withholding rate. A child born since, a mortgage signed before 2013, a parent in your care, a maintenance payment: none of that goes in by itself. 3. If something has changed, ask your HR department for a new form. The law lets you report changes when they happen, and the withholding is adjusted the following month.
And it works the other way round too: if you end up paying every year and it catches you at a bad moment, ask in writing for your rate to be raised. That you can request whenever you like, with no justification at all.