Skip to the calculator
Autónomo Simple Calculator
ESENDE
Try it free
Modelo 303 · output VAT − input VAT

Quarterly VAT calculator (Modelo 303)

Enter the taxable bases of your sales and purchases for the quarter, by VAT rate. You will instantly see whether your Modelo 303 is payable or carried forward, with the breakdown and the filing deadline. Everything is calculated in your browser.

  • Free
  • No sign-up
  • Indicative figures under current rules
Try it free for 14 daysHow it is calculated

Your quarter's figures

21%
10%
4%

Amounts without VAT. For purchases, only the part with deductible VAT.

Box 110: what is still pending and still valid.
Pre-filled example: replace it with your figures.

Calculated in your browser. We don't store what you type.

Result

VAT to pay in the Modelo 303 · Q3 2026€735.00Output €1,050.00 − input €315.00 = €735.00 (box 71).

Of the output VAT

  • Deductible input€315.00
  • To pay€735.00
Output VAT at 21%Base €5,000.00
€1,050.00
Total output VATBox 27
€1,050.00
Input VAT at 21%Base €1,500.00
−€315.00
Total deductible input VATBox 45
−€315.00
DifferenceBox 46: output − input
€735.00
Final resultBox 71 · negative = carried forward
€735.00

Q3 2026 deadline: from 1 October 2026 to 20 October 2026. With direct debit, until 15 October 2026. Confirm it in the AEAT calendar.

Excludes exempt operations, reverse charge, pro-rata and special regimes: they are reported separately and may change your real result.

Share result

The link opens this calculator with your figures already filled in. It carries no personal data.

Send via WhatsApp

Your Modelo 303 from your real invoices, without typing the bases by hand.

Try it free for 14 days
Never miss a deadline

Leave your email and we'll send you the upcoming filing deadlines (130, 303, annual return). No account, no spam.

We only store your email (not what you calculated). Unsubscribe in one click. Privacy

With Autónomo Simple

From a one-off sum to taxes that stay up to date

  • Your Modelo 303, calculated for you

    Output and input VAT come from your invoices and expenses, nothing typed twice.

  • Reminders before every deadline

    The tax calendar tells you when a return is due and which quarter you are closing.

  • Your data up to date, in one place

    Invoices, expenses and VAT in one account: less wrestling with spreadsheets at quarter-end.

How it works

How quarterly VAT is calculated

  1. Output VAT

    For each rate, taxable base of sales × rate (21% standard, 10% reduced, 4% super-reduced: arts. 90 and 91 of Law 37/1992). The total is the VAT you charged your customers.

  2. Deductible input VAT

    The same with the bases of your purchases and expenses with deductible VAT (arts. 92 et seq. of the VAT Act). If an expense is only partly deductible, enter only the deductible part.

  3. Result for the quarter

    Output − input VAT (box 46 of Modelo 303). If positive, you pay it; if negative, it is carried forward.

  4. Credit carried in

    If you carry VAT credit from earlier quarters, it is applied up to the amount payable (boxes 110 and 78). The final result is box 71.

What this calculation leaves out
  • Exempt operations (art. 20 of the VAT Act): no VAT and no box in the quarterly 303. Do not enter them here.
  • Reverse charge (for example, services bought from EU businesses without VAT): self-assessed and deducted at once, with no net effect if fully deductible. Do not enter it here.
  • Pro-rata, equivalence surcharge and special regimes (simplified, agriculture, cash basis).
  • Enter bases without VAT. VAT is computed line by line and rounded to cents, like the app's Modelo 303.
Legal references
Ley 37/1992, arts. 90 y 91
VAT rates: 21%, 10% and 4%.
Ley 37/1992, arts. 92 y ss.
Deduction of input VAT.
Ley 37/1992, art. 99.Cinco
Excess input VAT can be offset in later returns for four years from the filing that generated it.
Modelo 303, instrucciones de la AEAT
Boxes 46, 71, 72, 78 and 110 and filing deadlines.
Modelo 303

This same thing, with your real invoices, automatic.

Try it free for 14 days. No card to start.

  • Output and input VAT calculated from your invoices and expenses
  • A draft Modelo 303 for every quarter, always up to date
  • Tax calendar deadlines with reminders
  • Boxes and step-by-step guide on the Pro plan
Try it free for 14 daysCancel any time.
Illustrative example with made-up data.

What the Modelo 303 is

It is the quarterly VAT return for self-employed workers in the general regime: from the VAT you charged on your invoices you subtract the VAT you paid on deductible purchases and expenses. If the balance is in favour of the Tax Agency you pay it; if it is in your favour you carry it forward or, in Q4, request a refund.

When it applies and the deadlines

You file it every quarter while you are registered for VAT in the general regime. The deadline is 1 to 20 April, July and October, and 1 to 30 January for Q4; if the last day is a holiday or weekend it moves to the next business day. With direct debit the deadline ends earlier (generally 15 April, July and October and 25 January). Those under special regimes, such as modules or agriculture, follow other rules.

Common mistakes when calculating VAT

  • Entering amounts with VAT included: enter taxable bases, without VAT.
  • Deducting VAT on expenses unrelated to the business or without an invoice. If only part is deductible, enter only that part.
  • Declaring by payment date: in the general regime VAT belongs to the quarter of the transaction or invoice date, not when it is paid (except under the cash-basis special regime).
  • Mixing exempt or reverse-charge operations into the 303 as if they were 21% sales.
  • Forgetting credit from earlier quarters, or applying it after the four years have passed.
FAQ

Frequently asked questions

How is the VAT payable each quarter calculated?
You add up the output VAT (base of each sale × its rate) and subtract the deductible input VAT on your purchases and expenses. The result is box 46 of Modelo 303. If positive you pay it; if negative it is carried forward.
What if input VAT is higher than output VAT?
The result is negative and is offset in later returns. The VAT Act (art. 99.Cinco) allows this for four years from the filing that generated it. In Q4 you can also request a refund, but then you cannot offset that amount later.
What is the deadline for the Modelo 303?
1 to 20 April (Q1), July (Q2) and October (Q3), and 1 to 30 January (Q4). If the last day falls on a weekend or holiday it moves to the next business day. With direct debit it ends earlier. The calculator shows the dates for the quarter you choose.
Do exempt or reverse-charge invoices go in this calculator?
No. Exempt operations carry no VAT and have no box in the quarterly 303, and under reverse charge the VAT is self-assessed and deducted at once, with no net effect if fully deductible. They are reported in their own boxes but do not change this calculator's result.
Which input VAT on my expenses can I deduct?
VAT on expenses related to the business and backed by an invoice, under arts. 92 et seq. of the VAT Act. If an expense is only partly deductible (for example, mixed use), enter only the deductible part of the base.

Try Autónomo Simple free for 14 days

Load your invoices and expenses and see your quarter estimates. No card to start. After that you choose a plan: Basic €10/mo or Pro €18/mo, VAT included, billed monthly.

Try it free for 14 daysSee plans and pricing
More tools

Keep going with these tools and guides

Articles and guides

Figures are approximate estimates calculated from the data you enter or import, and may differ from the official assessment. Autónomo Simple is not tax, accounting or legal advice. If in doubt, check with a gestor. More in the Terms. The figures you enter are calculated in your browser and are not stored (only your email, if you ask for the deadlines).

© 2026 Autónomo Simpleautonomo-simple.es
Try it free for 14 days