How to fill in the modelo 303 step by step (a practical guide for autónomos)

The modelo 303 is the form that every autónomo (self-employed worker) files each quarter to declare VAT (IVA). If you already know how quarterly VAT is calculated, filling it in is just a matter of knowing which figure goes in each box. And out of the sixty-plus boxes the form has, most of them don’t affect you.

This guide goes box by box, with a real example, so you can sit down in front of the Spanish Tax Agency (Agencia Tributaria) form and complete it without hesitation.

This guide covers the modelo 303, used in the common territory and (with deadline nuances) the Basque Country. If you pay tax in Navarre, your VAT form is the F-69, with its own boxes. In the “Before you open the form” section there’s a “Where do you pay tax?” selector summarising which form and deadlines apply to you; the boxes explained afterwards are those of the 303.

The example we’re going to use

Marta is a freelance graphic designer. In the second quarter of the year she has issued three invoices to Spanish clients and received five invoices for deductible expenses.

Invoices issued (income):

Invoices received (deductible expenses):

With these figures we can already do the maths: 1,575 euros of output VAT (IVA repercutido) minus 174.30 euros of input VAT (IVA soportado) = 1,400.70 euros to pay. If you need to review exactly what input and output VAT are, it’s worth being clear on that before going on. If you want to run the quick calculation with your own figures, use the quarterly VAT calculator.

Now it’s time to transfer those numbers to the form.

Before you open the form

This guide follows the modelo 303 of the common territory. If you pay tax under a regional (foral) regime, the form and some deadlines change:

To file the modelo 303 you need to access the Agencia Tributaria’s electronic office with a digital certificate, electronic DNI or Cl@ve PIN. Once inside, look for “Modelo 303” in the VAT procedures section and select the relevant quarter.

The form will ask for your NIF (tax ID), name, tax year and period (1T, 2T, 3T or 4T). Fill in those identifying details and you’ll reach the body of the form, which is organised into three main blocks: output VAT, deductible VAT and result.

Block 1: output VAT (boxes 01 to 26)

This block gathers all the VAT you’ve charged your clients during the quarter. The Agencia Tributaria calls it “IVA devengado” (output VAT) or “régimen general” (general regime).

Boxes 01 to 09: operations by VAT rate

Here you declare your sales grouped by tax rate. There are three rows, one for each rate:

• Boxes 01, 02, 03: operations at the general rate of 21%.
• Boxes 04, 05, 06: operations at the reduced rate of 10%.
• Boxes 07, 08, 09: operations at the super-reduced rate of 4%.

In each row, the first box is the number of operations (not the amount: how many invoices), the second is the taxable base and the third is the tax due (base times rate).

In Marta’s case, who only invoices at 21%:

• Box 01: 3 (three invoices issued).
• Box 02: 7,500.00 (sum of the taxable bases).
• Box 03: 1,575.00 (7,500 times 0.21).

Boxes 04 to 09 stay at zero because she has no operations at reduced rates.

Boxes 10 to 26: special operations

These boxes cover intra-Community acquisitions (purchases from suppliers in other EU countries), reverse-charge operations, modifications of taxable bases and recargo de equivalencia (the equivalence surcharge regime for retailers).

If your activity is only with Spanish clients and suppliers, and you don’t apply recargo de equivalencia, all these boxes stay at zero. The vast majority of autónomos with a simple activity don’t touch anything here.

Box 27: total output VAT due

It’s the sum of all the output VAT due. For Marta: 1,575.00 euros.

Block 2: deductible VAT (boxes 28 to 44)

This block gathers the VAT you’ve paid your suppliers and can deduct. Not every expense is deductible: only those directly related to your professional activity and which have a complete invoice with your tax details count.

Boxes 28 and 29: purchases of current goods and services

This is where the bulk of your ordinary deductible expenses go.

• Box 28: 829.99 (sum of the taxable bases of the expenses).
• Box 29: 174.30 (sum of the VAT on those expenses).

Boxes 30 and 31: investment goods

If during the quarter you’ve bought an investment good –a computer, a camera, office furniture– whose amount exceeds 3,005.06 euros (net, without VAT), it’s declared here instead of in boxes 28-29. The VAT is still deductible, but it goes in a separate box because investment goods have special regularisation rules over the following years.

Marta hasn’t made any purchases of this kind this quarter, so boxes 30 and 31 stay at zero.

Boxes 32 to 43: other deductions

Imports, intra-Community acquisitions, agricultural regime compensations and other situations that don’t apply to most autónomos with a domestic activity. Leave at zero unless one of them applies to you.

Box 44: total to deduct

It’s the sum of all the deductible VAT. For Marta: 174.30 euros.

Block 3: result (boxes 45 to 71)

This is where everything is reconciled.

Box 45: difference

Box 27 minus box 44. That is, output VAT minus deductible VAT.

For Marta: 1,575.00 - 174.30 = 1,400.70 euros.

Box 46: amounts to offset from previous periods

If in some earlier quarter of the same year the result was negative and you chose to offset it (instead of requesting a refund), here you subtract that amount. If you have nothing pending, you leave it at zero.

Box 64: result of the settlement

It’s the result after applying offsets and other adjustments. For most autónomos it’s the same figure as box 45. Marta puts: 1,400.70 euros.

Box 65: exclusively for the last return of the year

In the fourth quarter (4T), this box allows you to include the annual regularisation of investment goods, if applicable. In the first three quarters it’s left at zero.

Boxes 66 to 69: annual result

These boxes are only filled in in the fourth quarter. They gather the overall result of the year, the offsets applied, the refund requested, etc.

Box 71: result of the settlement

This is the final number. It’s what you pay or what you get refunded.

For Marta, in the second quarter: 1,400.70 euros to pay.

If the result is positive, select “A ingresar” (to pay) and choose direct debit or direct payment with NRC. If it’s negative, select “A compensar” (to offset) to deduct the amount in later quarters, or “A devolver” (to refund) if you’re in the fourth quarter and you want the Agencia Tributaria to pay you the difference.

What happens if the result is negative

If in a quarter you’ve paid more VAT than you’ve charged –for example, because you had a large investment or a quarter with little income– the result of the settlement will be negative.

In the first three quarters of the year you have two options:

Offset: you leave that balance in your favour to subtract it in the next quarter. You mark “A compensar” in the relevant box and carry the amount forward.

Wait until the fourth quarter: in the last return of the year you can request a refund of the accumulated balance. It’s the only return in which the Agencia Tributaria refunds you money directly.

You can’t request a refund in the first, second or third quarter except in very specific cases (cessation of activity, for example). The usual thing is to offset and keep carrying it forward.

The most common mistakes

Not including all the deductible expenses. Every expense invoice with VAT that you forget to record is money you pay over the odds. Reviewing the quarter’s bank statement before filing the return is a habit that pays off.

Confusing the taxable base with the total amount. Box 02 asks for the taxable base, not the invoice total. If your invoice is for 2,420 euros (2,000 base + 420 VAT), in box 02 you put 2,000. It seems obvious, but under deadline pressure it happens more than it should.

Not keeping the invoices. The modelo 303 is a return, not a definitive settlement. The Agencia Tributaria can ask you for the original invoices in a later check. You need to keep them for at least four years.

Filing late. The modelo 303 deadlines are strict: in the common territory, from the 1st to the 20th of the month following the close of the quarter (except the fourth, until 30 January); in the Basque Country, until the 25th (with the fourth quarter in the annual modelo 390); and in Navarre, with the modelo F-69. You have them by territory at the start of the article. If you direct-debit the payment, the deadline ends five days earlier. Filing late, even by a single day, can trigger surcharges.

Forgetting the offsets. If the previous quarter came out negative and you marked “A compensar”, that amount should appear in box 46 of the next quarter. If you forget it, you’re giving up that balance in your favour.

Quick summary for Marta

Seven boxes with real figures, the rest at zero. That’s all an autónomo with a simple activity needs to fill in.

How does Cuéntamo help with this?

Filling in the modelo 303 by hand means adding up your invoices again, splitting the VAT by rate, and making sure the boxes are consistent with each other. If you keep your transactions in Cuéntamo, that work is already done: the self-employed module calculates the quarterly settlements from the transactions you’ve recorded, with output and input VAT broken down by rate. You just copy each total into its box on the Agencia Tributaria form.

The breakdown by VAT rate is expandable, so you can see which invoices make up each box and review them before filing. If a quarter comes out as carry-forward (VAT to compensate), the amount rolls over to the next one without you having to remember it.

Before tackling the full form, you can check the result with the quarterly VAT calculator. And if you want to understand where each number comes from, review how quarterly VAT is calculated.

Frequently asked questions

Which boxes of the modelo 303 do I have to fill in if I’m an autónomo with a simple activity?

If you only invoice at 21% to Spanish clients and your expenses are ordinary, just a few are enough: the output VAT boxes (01, 02, 03), the total output VAT due (27), the deductible VAT boxes (28, 29), the total to deduct (44) and the result boxes (45, 64 and 71). The rest stay at zero.

What do I put in box 02, the taxable base or the invoice total?

The taxable base, not the total. If your invoice is for 2,420 euros (2,000 of base plus 420 of VAT), in box 02 you put 2,000. It’s one of the most repeated mistakes.

What do I do if the result of my modelo 303 comes out negative?

In the first three quarters you can mark “to be offset” and carry that balance in your favour forward to the next quarter. The refund is only requested in the fourth quarter, except in specific cases such as cessation of activity.

Where do I declare the purchase of a computer or a capital asset?

If it exceeds 3,005.06 euros of taxable base it goes in boxes 30 and 31 (investment goods), not in 28-29, because they have their own regularisation rules. Below that amount it’s declared as an ordinary expense.

How long do I have to keep the modelo 303 invoices?

At least four years. The 303 is a return, not a definitive settlement, and the Agencia Tributaria can ask you for the original invoices in a later check.

If you keep your transactions in Cuéntamo, the amount for each box is already calculated for you on the quarterly settlements screen. You just have to copy the totals to the Agencia Tributaria form. Available at cuentamo.com.

Figures for 2026. The general (21%) and reduced (10%) VAT rates have been in force since 2012 (RDL 20/2012); the super-reduced rate (4%), since 1995 (Law 37/1992 on VAT).

This article is checked against official sources and reviewed periodically. If you spot anything out of date, email us at [email protected].