Modelo 303 estimator (quarterly VAT)

How the 303 works in two lines

Modelo 303 is Spain's quarterly IVA (VAT) return, and at heart it is a subtraction:

• IVA repercutido (output VAT): the tax you add to your sales invoices and collect from your clients.
• IVA soportado deducible (deductible input VAT): the tax you pay on the purchases and expenses of your business.

Output VAT minus input VAT. If the result is positive, you pay the difference to Hacienda (the Spanish tax office); if it is negative, it is in your favour and you carry it forward to later quarters. That is exactly what this calculator estimates from the bases you enter.

What this estimate does and does not cover

The calculator does the essentials: it takes the base (net, pre-VAT amount) of your sales and of your expenses, applies the IVA rate you choose, and returns the output VAT, the input VAT and the difference. That is enough for many autónomos (self-employed workers in Spain) with straightforward billing and a single rate.

What it does not handle, and what can move your real figure, are the special situations of the tax:

• Intra-EU operations: sales or purchases with EU businesses, which have their own boxes and are also declared in modelo 349.
• Inversión del sujeto pasivo (reverse charge): invoices where the VAT is accounted for by the recipient, not the issuer.
• Regla de prorrata (pro rata rule): when you can only deduct part of your input VAT because your activity mixes operations with and without the right to deduct.
• Capital goods (bienes de inversión): asset purchases with their own deduction rules spread over several years.
• Criterio de caja (cash basis): the regime where VAT is due when you get paid and when you pay, not when you invoice.

If any of these appear in your quarter, the real result will differ from what you see here. That is why it is an orientation, not a closed calculation.

The VAT you collect is not yours

This is the point worth getting straight: the IVA you add to your invoices is not your income. You collect it from your client on behalf of Hacienda and hold it until the 303. When the quarter closes, you hand that money back, minus the VAT you paid on your own expenses.

The practical takeaway: if you spend the VAT you collected, it may be missing come April, July, October or January. Treat it as money passing through and set it aside as soon as it lands. To work out how much to reserve each month across VAT and income tax, use the how much to set aside for taxes calculator.

The IVA rates you can choose

Spain has three IVA rates, and in the calculator you pick the one that fits your activity:

• General, 21%: the default rate, for most goods and services.
• Reduced, 10%: for example hospitality, passenger transport and certain products.
• Super-reduced, 4%: bread, milk, books, medicines and other basic essentials.

The rates are set in articles 90 and 91 of the Spanish VAT Act. The tool applies one rate to all your bases; if in the same quarter you invoice at different rates, add up each block separately to get closer to the real result.

An estimate, not your return

The number you see is indicative. Your real 303 depends on each invoice being correctly classified, on the input VAT actually being deductible, and on the special situations this tool does not compute. Before filing, reconcile the figures with your libros registro (VAT record books) and, if in doubt, with a professional. For the whole form, its deadlines and the possible outcomes, see the modelo 303 guide.

If you keep your invoices and expenses in kontora, the app builds the 303 draft box by box from your real invoices and flags the deadlines; filing it is still up to you. This calculator, by contrast, is only a quick estimate to orient you.

Frequently asked questions