The end of the quarter is approaching, and with it, one of the most important tax obligations for freelancers and SMEs in Spain: filing the Form 303 VAT self-assessment. With a reference date of September 2026, the deadline for the third quarter (July-September) is from October 1st to 20th. Preparing it correctly is key to avoiding errors and potential penalties.
In this article, we'll guide you step by step and explain how the imminent arrival of electronic invoicing and VeriFactu is transforming this process.
What do you need to get started?
Form 303 is the declaration where you report to the Spanish Tax Agency the VAT you have charged your clients (output VAT) and the VAT you have paid on your deductible expenses (input VAT). The difference will determine whether you have to pay the tax authorities, if the result is zero, or if you have a balance in your favor to be compensated in future quarters.
To prepare it, organization is your best friend. You will need:
- All invoices issued during the quarter.
- All invoices and receipts from expenses related to your business activity.
- A clear understanding of the different VAT rates applied (general 21%, reduced 10%, and super-reduced 4%).
Steps to complete Form 303
1. Calculate Output VAT: Sum the taxable bases of all your sales invoices, group them by VAT rate, and calculate the total VAT amount you have charged.
2. Calculate Deductible Input VAT: Do the same with your expense and purchase invoices. Sum the bases and VAT amounts you have paid, as long as they are deductible expenses for your activity.
3. Get the result: The formula is simple: Output VAT - Deductible Input VAT = Self-assessment Result.
If the result is positive, you must pay this amount to the Tax Agency. If it's negative, you can request a refund (only in the last quarter of the year) or offset it in subsequent declarations.
Digitalization and VeriFactu: Your new VAT ally
Although the full mandatory implementation of VeriFactu is approaching (July 1, 2027, for freelancers), getting ahead is the smartest strategy. Adapted invoicing software not only ensures you comply with future regulations but also greatly simplifies the preparation of Form 303.
These systems automate the recording of income and expenses, calculating VAT bases and amounts in real time. This minimizes human error and saves you hours of manual work. If you still use traditional methods, it's time to consider a change. In fact, many questions arise about whether you can continue invoicing in Excel or Word with VeriFactu, and the answer is that under the new regulation, it won't be possible if they don't meet the integrity and inalterability requirements.
For businesses with more complex systems, the transition must be planned. It is essential to ensure a proper integración ERP VeriFactu or use a API VeriFactu to connect custom tools. Data migration is another key point, whether it's to importar Factusol a VeriFactu or to importar Sage 50 and other programs like importar Holded. Forget about trying to importar Excel a VeriFactu; the law requires a guaranteed invoicing system. You can check the key dates in our guide on when is VeriFactu mandatory for freelancers?.
Preparing Form 303 no longer has to be a tedious task. With tools like the invoicing software from Fakturia.es, which is adapted to the Anti-Fraud Law and VeriFactu, you can automate your calculations and file your taxes with the peace of mind that all your information is organized and correct.