Carmen is a self-employed architect in Salamanca. In 2025 she invoiced 50,000 € to Spanish clients and 30,000 € to an architecture studio in Munich for which she develops projects. Her gestoría (accountancy firm) correctly declared the German invoices on Modelo 349, as services to another EU country, but on the 390 (the annual VAT summary) it put them in the box for exempt transactions. And, consistent with that error, on the fourth-quarter Modelo 303 (the quarterly VAT return) it applied a pro rata (prorrata): if part of her transactions were exempt without the right to deduct, she could only deduct part of her input VAT. Carmen lost 1,480 € of deductible VAT. She found out in March 2026, when discussing her annual summary with a colleague who had a client in France and had not had that problem.
The error, explained without jargon
The professional services Carmen provides to a business established in Germany are not treated as supplied in Spain: they are located where the client is, and it is the client who accounts for VAT in its own country. For Carmen they are transactions not subject to Spanish VAT under the place-of-supply rules. And the Spanish VAT Act recognises that those transactions carry the right to deduct, because had they been supplied in Spain they would have been taxed. They are not exempt, and they do not reduce the VAT that can be deducted.
By putting them down as exempt on the 390, the gestoría created a double problem. It declared information that contradicts what was declared on the 349, and it applied a pro rata that did not apply.
What the wrongly applied pro rata cost
| Item | What the gestoría did | The correct treatment |
|---|---|---|
| Transactions in Spain with VAT | 50,000 € | 50,000 € |
| Services to the Munich studio | 30,000 € as exempt | 30,000 € not subject, with the right to deduct |
| Pro rata percentage | 50,000 / 80,000 = 62.5 %, rounded up to 63 % | No pro rata: 100 % |
| Input VAT for the year | 4,000 € | 4,000 € |
| Deductible VAT | 2,520 € | 4,000 € |
| Difference | 1,480 € under-deducted | |
The pro rata is rounded up to the next whole number, which is why 62.5 % becomes 63 %. In the last quarter of the year the gestoría adjusted the difference between what had been deducted in the first three, at 100 %, and the annual 63 %, and that adjustment made the fourth-quarter 303 come out 1,480 € higher.
How it is corrected, and in what order
Two different things have to be fixed, and the order matters. First, the fourth-quarter 303, which is where the money is: it is corrected to remove the pro rata adjustment and recover the 1,480 € overpaid. Depending on the Modelo and the year, that correction is made with a rectifying return or an application for rectification (solicitud de rectificación); the form in force decides which, and it is the first thing to check. If there was an undue payment, the refund carries interest in the taxpayer's favour.
Then the 390: a new return is filed replacing the previous one, with the German transactions in their proper place, as not subject with the right to deduct, and without a pro rata. That way the annual summary tells the same story again as the 349 and the quarters. Fixing only the 390 and leaving the 303 as it was would be correcting the paper and not the money; fixing only the 303 would leave an annual summary that contradicts the correction.
If you have clients in other countries and suspect your VAT is not properly reflected, tell us in the self-employed form. With the year's 349, 390 and 303s, it is quickly clear whether there is a classification problem.
Who answers, and what is claimed
As far as the Agencia Tributaria is concerned, the person liable is Carmen. She is the one who files the rectification, receives the refund and answers if the Administration asks about the change. In this case the error worked against her, so what has to be done is to recover, not to pay. The refund, with interest, leaves Carmen almost as if nothing had happened.
It is advisable, though, to accompany the rectification with a brief, documented explanation: the invoices to the Munich studio, its VAT identification number and the 349 filed. A rectification that explains the change by itself is resolved sooner than one that forces the Administration to ask.
As against the gestoría, the damage that can be claimed is therefore small: the cost of the rectification and, if you wish, the fee for a job badly done. If the error had been the opposite, for example transactions that really were exempt declared as taxable and VAT over-deducted, the situation would be different: the Administration would claim the difference with interest and, if it got there first, with a penalty, and the damage attributable to the adviser would be precisely that interest and that penalty. Never the tax itself, which was owed anyway. The route is civil, based on the contract and on the professional's indemnity insurance, and the decisive evidence is what information the gestoría had: here, the very 349 it filed shows that it knew the client was German.
The Agencia Tributaria cross-checks what you declare on the 349 against what your client declares in its own country, through the European system for exchanging information, and against what you yourself put in the annual summary. If the 349 says «intra-Community services» and the 390 says «exempt», the question will come sooner or later. It is better that it arrives with the correction already filed.
The error that spreads to the following year
The pro rata has a memory. During each year, deductions are made at a provisional percentage, which is the final percentage for the previous year, and in the last quarter it is adjusted to the final one for the current year. If the 63 % for 2025 is left as it is, the first three quarters of 2026 will also have been deducted at 63 %, and Carmen will have been overpaying since January without knowing it. When correcting 2025, the 303s already filed for 2026 also have to be reviewed and the difference recovered in them, or left to be adjusted in the last quarter of the year if the rules allow it in that case.
That is why, when a classification error is found in an annual summary, the review is not limited to the year in which it was made. Its trail is followed forward to the last quarter filed. In Carmen's case, the final picture was 1,480 € from 2025 plus about 900 € from the first three quarters of 2026, all recoverable with interest by way of rectification. The right to claim it expires after four years, so there is no extreme urgency, but each quarter that passes with the wrong pro rata adds another rectification to the list.
What almost nobody tells you about errors in the annual summary
The 390 is where classification errors show. On the quarterly 303 transactions are grouped together and a mistake like this can go unnoticed; on the annual summary, with each type of transaction in its own box, it stands out for anyone who knows how to read it. That is why, when someone changes adviser, we always ask for the last 390 first: on one page it tells how VAT has been handled over a whole year. If your clients are abroad, the guides to where each service is taxed and to the reverse charge explain the underlying treatment.