Modelo 303: Spain's VAT return, deadlines and input VAT boxes

If you are self-employed or run a company in Spain, the Modelo 303 is the form that sets your VAT bill every quarter. It brings together the VAT you charged on your sales and the VAT you paid on your costs, and it is one of the documents your asesor fiscal works on most often.

What the Modelo 303 is

The Modelo 303 is the VAT self-assessment (autoliquidación del IVA) filed with the Agencia Tributaria (AEAT). The AEAT's practical manual states that the same form is used whether your VAT period is quarterly or monthly (AEAT manual, as of October 2026). The form has a section for VAT accrued on your sales (IVA devengado) and a section for deductible input VAT (IVA deducible); the difference between the two is the result of the return.

The AEAT offers the Pre303 service on its electronic office to prepare and file the form (AEAT, Modelo 303, as of October 2026).

Who files it

Article 71.1 of the Spanish VAT Regulation (Real Decreto 1624/1992) requires businesses and professionals to file the periodic VAT returns even if they charged or deducted no VAT in the period. The exception is anyone who only carries out VAT-exempt operations under articles 20 and 26 of the VAT Act (BOE, as of October 2026).

Under the VAT group regime the monthly return is a different form (modelo 322), and VAT taxpayers must also file an annual summary, the modelo 390, unless an exemption applies, for example for those who keep their books through the SII (AEAT manual).

Periods and deadlines

By default the VAT period is the calendar quarter (article 71.3). It is the calendar month instead for, among others, businesses whose turnover exceeded €6,010,121.04 in the previous year, those registered for monthly refunds and VAT groups.

Deadlines for quarterly filers according to the AEAT (as of October 2026):

In the fourth-quarter return you can also request a refund. Monthly filers file from the 1st to the 30th of the following month, and the January return is due by the end of February.

The boxes for deductible input VAT

For a business that mostly buys goods and services in Spain, the key boxes in the deductible section are (AEAT Pre303, as of October 2026):

In Pre303, box 28 adds up the taxable bases and box 29 the deductible VAT of received invoices whose deductible VAT is above zero and whose registered period matches the return. Boxes 30 and 31 apply the same logic to invoices flagged as capital goods. Further boxes in the same section cover imports, intra-EU acquisitions and corrections.

Preparing it from your books

Since 2022, businesses that are not in the SII can import their VAT books into Pre303 to fill in the form automatically. The import requires the AEAT's standard XLSX format, at most 4 MB, with all entries from 1 January to the end of the quarter in one file (AEAT specifications, as of October 2026). That is why a clean libro registro de facturas recibidas matters: boxes 28 and 29 come straight from it.

Typical mistakes are deducting invoices in a period before they were received, mixing capital goods into boxes 28 and 29, and missing the shorter deadline when paying by direct debit.

How Bonro helps prepare it

Bonro creates a preparatory PDF per quarter (1T–4T). It is not an AEAT submission: your asesor fiscal, or you, still file the Modelo 303 on the AEAT's electronic office. The PDF shows box 28 (taxable base) and box 29 (input VAT) for current domestic purchases, a breakdown by VAT rate (21, 10, 4 and 0 %) and the list of receipts behind the totals.

Boxes 30 and 31 for capital goods are left at 0 with a note for your asesor, and the output VAT section is out of scope because Bonro tracks expenses, not issued invoices. You can check and correct every receipt field before exporting. The Modelo 303 PDF is part of the Pro plan; see Bonro's pricing for details.