Form 303: How to Prepare Your Quarterly VAT Return
Form 303 is one of the most important tax filings for any freelancer or SME in Spain: the quarterly VAT self-assessment. With a reference date of September 2026, we are in the final stretch to prepare the third quarter's return. Furthermore, we are on the verge of a crucial regulatory change: the implementation of VeriFactu.
Below, we guide you step-by-step to file your Form 303 without errors and get ahead of the new requirements.
1. Information Gathering: The Foundation of Everything
Before accessing the Spanish Tax Agency's (AEAT) online portal, you need to have all your accounting data organized. This is divided into two main blocks:
* Output VAT (Income): Gather all the invoices you have issued to your clients during the quarter. For each one, you need the tax base and the applied VAT amount (21%, 10%, or 4%). The sum of all the VAT from your sales is the VAT you have collected and must pay to the Tax Agency.
* Input VAT (Expenses): Collect all invoices for deductible expenses and purchases related to your business activity. It is essential that they are complete invoices, not simplified receipts without your tax details. The sum of the VAT from these expenses is the VAT you can deduct.
This process, while simple in theory, can be tedious. The arrival of VeriFactu systems, as we explain in our guide on what VeriFactu is, will automate much of this record-keeping, minimizing errors.
2. The Transition to VeriFactu and Its Impact on VAT
Although VeriFactu will not be mandatory until January 1, 2027, for companies and July 1, 2027, for freelancers, the transition is already underway. Adapting your invoicing now will not only save you from last-minute rushes but will also greatly simplify your tax preparation.
Many businesses are planning their VeriFactu ERP integration or connecting their systems via a VeriFactu API. Questions arise about how to import Factusol into VeriFactu, or migrate data from Sage 50 or Holded. Even those using spreadsheets are looking for ways to import Excel into VeriFactu securely. For developers, a VeriFactu gateway for software is the solution to adapt existing applications.
You can check the full calendar in our guide on the VeriFactu deadlines for 2027.
3. Filling Out Form 303
With your total output and input VAT calculated, the process on the AEAT website is as follows:
1. Identification: Fill in your personal or company details.
2. Output VAT: Enter the total tax bases and VAT amounts, broken down by VAT rate (standard, reduced, super-reduced).
3. Deductible VAT: Enter the tax bases and VAT amounts from your expenses and purchases.
4. Result: The system will automatically calculate the difference.
* Positive result: This is the amount to be paid to the Tax Agency.
* Negative result: This means you have paid more VAT than you have collected. You can request a refund (only in the last quarter of the year) or carry it forward to offset against the next return.
Anticipating the regulations is the best strategy. An invoicing software like Fakturia.es, already compliant with the Anti-Fraud Law and VeriFactu requirements, not only ensures you comply with the law but also turns the preparation of Form 303 into a simple and almost automatic task.