Why your payroll withholding differs from what you owe

Key rules

• Retención: Withholding is an advance payment, so a refund or a balance due is normal.
• Modelo 145: If you do not give your employer the form, they withhold at a higher rate.
• Second employer: Two payers often mean too little is withheld, so you may owe tax.
• Refunds: The tax agency must pay refunds within six months of the end of the filing period.

The short answer

The retención on your payslip is an advance estimate, not your final tax. The annual Renta return settles the difference. If too much was taken, you get a refund. If too little was taken, you pay the balance.

How your employer sets the percentage

Your employer estimates your pay for the year. From that they subtract social security contributions and a general expense allowance. Then they apply allowances based on your personal and family situation: marital status, children, dependants and disability. The tax scale gives an annual tax figure. Divided by your annual pay, it gives a percentage, which is applied to every payment.

The tax agency publishes a calculator and tables, so you can check your own percentage. Below certain minimum pay levels, no withholding applies.

Your part: the personal circumstances form

You give your employer the modelo 145 when you start work. It goes to the employer, not the tax office. Update it within 10 days of any change, such as a new child or a change in marital status.

If you never give it, your employer withholds as if you had no family circumstances. That means higher withholding. You get the difference back when you file your return.

Why withholding and your real tax differ

• Your pay changed during the year.
• You have other income, such as a second employer, rental income or savings.
• Your circumstances changed, or were reported wrongly.
• Some deductions are not counted in withholding, such as pension plan contributions, rent or regional deductions.
• Tax rules differ by region.

A second employer is a common cause of owing tax. Each employer withholds as if they were your only one, so the total is often too low.

How the result is worked out

Your return calculates tax on your total income and applies your deductions. The withholdings already paid are subtracted. If the result is positive, you pay it. If it is negative, the tax agency refunds you.

The filing campaign usually runs from April to 30 June. Payment by direct debit closes a few days earlier. You can split payment in two: 60% by the June deadline and 40% by 5 November. The tax agency must pay refunds within six months of the end of the filing period. After that, it owes you interest.

Use the checklist, timeline and decision below to plan your steps.

Choosing between options

How do you handle the result of your annual return?

• Collect a refund: Your withholdings were higher than the tax you owe, so the result is negative and the tax agency pays you back.

• Pay in full by June: Your withholdings were lower than the tax you owe and you want to settle it at once, by 30 June (direct debit closes a few days earlier).

• Pay in two instalments: You owe tax and prefer to pay 60% by the June deadline and the remaining 40% by 5 November.

Take the tax on your total income after deductions and subtract the withholdings already made. If the result is positive, you pay it; if negative, you get a refund.

Timeline and deadlines

• Give your employer the personal circumstances form: when you are hired

• Pay the second instalment if you split the payment (40%): by 5 November

Documents you need

• Personal circumstances form (modelo 145): you fill it in and give it to your employer, not the tax office, when you start a job and within 10 days of any change in your situation. It covers date of birth, marital status, children, dependants and disability.

Checklist

• Give your employer the personal circumstances form when you start work.

• Check that the marital status, children, dependants and disability on the form are correct.

• Update the form whenever your circumstances change.

• Compare the withholding percentage on your payslip with the result from the tax agency's calculator.

• Keep your annual payslip summary to compare total withholding with your final tax in the annual return.

Frequently asked questions

What happens if I never give my employer the personal circumstances form?

Your employer withholds as if you had no family circumstances, so more tax is taken from each payslip. The extra is not lost: you get it back through the annual return if it turns out you overpaid.

How soon must I tell my employer when my family situation changes?

You must tell your employer within 10 days of the change, using the personal circumstances form (modelo 145). You give it to the employer, not to the tax office. Your withholding rate is then recalculated.

Can I pay the balance due in instalments?

Yes, you can split the payment into two parts: 60% by the June deadline and 40% by 5 November. Direct debit payment ends a few days before the 30 June closing date of the campaign.

How long does the tax agency have to pay my refund?

The AEAT, Spain's tax agency, must pay your refund within six months of the end of the filing period. If it pays later, it owes you interest.

Why can a second employer leave me owing tax?

Yes, a second employer can cause under-withholding, so you may owe tax even though both employers withheld. Each one calculates the rate on its own pay, and the annual return adds both incomes together.