An error when entering quarterly sales in an OSS VAT return filed in Spain can result in a tax assessment for thousands of euros. The problem becomes particularly serious when the Spanish Tax Agency does not dispute that you reported an error, but argues that you have not provided enough evidence to establish the correct figures.
The decisive question is this: if you accidentally overstated your sales in Spain’s Form 369, can the Spanish Tax Agency maintain the resulting assessment even after you provide invoices, orders and accounting records showing the actual transactions? It should not do so without examining that evidence fully and giving proper reasons for its decision. However, obtaining the cancellation or recalculation of the assessment requires more than simply stating that a mistake occurred. You must turn the error into a verifiable fact.
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Can the Spanish Tax Agency maintain an OSS assessment if you have proved that the return was incorrect?
The answer depends on the quality and consistency of the evidence. If your documents identify the actual sales made during the quarter, verify the invoices issued and connect each transaction with the corresponding orders, the Spanish Tax Agency should not merely state that the error has not been proved. The AEAT must examine the evidence as a whole and explain why it accepts or rejects your reconstruction.
In the case considered here, a foreign business included a total amount of €119,582.45 in its Spanish OSS VAT return for the fourth quarter of 2023. Applying the reported rate of 7% resulted in a taxable amount of €111,759.30 and VAT of €7,823.15.
However, the actual transactions for the quarter totalled only €9,337.14, including VAT: a taxable amount of €7,716.64 and VAT of €1,620.50 at 21%. This was not a minor discrepancy or a disagreement about the interpretation of Spanish VAT legislation. It was a data-entry error that directly affected the amount demanded by the Spanish tax authorities.
«Instead of the correct revenue amount of EUR 9,337.14, the amount of EUR 119,582.45 was entered into the system by mistake».
The initial Spanish tax assessment for the four quarters of 2023 resulted in an amount payable of €20,572.74. Following an administrative reconsideration appeal, known in Spain as a recurso de reposición, the amount was reduced to €17,000.54. Nevertheless, the AEAT maintained the fourth-quarter adjustment because it considered that the additional error had not been sufficiently proved.
This is the key point for your Spanish VAT dispute: an incorrect amount may still be corrected after the AEAT has issued an assessment, but your explanation must be consistent with the invoices, orders, accounting records and VAT calculations.
OSS VAT errors in Spain: what you need to prove
En este vídeo te explico de forma clara el problema central del artículo y qué puntos deberías revisar antes de contestar.
La idea es que puedas entender rápido la tesis del expediente antes de entrar en el análisis completo.
Debajo tienes el análisis completo para revisar dónde puede estar la clave del expediente.
What happened in the Spanish OSS VAT return for the fourth quarter of 2023?
The EU One Stop Shop allows businesses to declare certain cross-border VAT transactions through a single Member State. A foreign company may therefore use Spain as its Member State of identification and file its OSS VAT returns with the Spanish Tax Agency. In Spain, these returns are generally submitted using Form 369.
This system simplifies VAT compliance across the European Union, but it does not eliminate the risk that an amount entered incorrectly may artificially multiply the tax payable. When Spain is the Member State handling the OSS return, any resulting assessment or dispute may have to be dealt with through Spanish tax procedures.
In this case, the dispute did not concern the first three quarters of 2023. The central issue was Q4. The company informed the AEAT that it had entered an incorrect figure, but during the initial review it provided only a stamped table showing the amounts originally reported and the figures it considered correct.
For the Spanish Tax Agency, that table was insufficient. The practical problem is easy to understand: a spreadsheet prepared by the business states what the result should have been, but does not necessarily prove the transactions behind that result. The AEAT wanted evidence capable of demonstrating the economic reality underlying the requested correction.
«In the opinion of this Office, the additional error made in the OSS return for the fourth quarter of 2023 has not been proved».
If this is happening to your business, you should not respond by sending the same spreadsheet again or merely insisting that the reported amount is impossible. You need to show how the correct figure is calculated and why the amount declared cannot correspond to the transactions carried out during the relevant period.
The error must be capable of reconstruction
A strong explanation should allow the Spanish tax authorities to follow the complete sequence: sales made, invoices issued, taxable amount, applicable VAT rate, VAT due and total amount charged. If the mistake also affected the VAT rate or the type of amount entered—for example, if gross revenue was confused with the taxable amount—you should explain this expressly.
In this case, the correct total of €9,337.14 could be broken down and verified: €7,716.64 as the taxable amount and €1,620.50 as VAT at 21%. That calculation matched the invoice summary, the individual invoices and the orders for the quarter. The corrected figure was therefore not an unsupported alternative: it was confirmed by several sources that could be checked against one another.
What evidence can prove an error in Spain’s Form 369?
The strength of an appeal against a Spanish OSS VAT assessment usually lies in traceability. The objective is not to submit as many files as possible. It is to ensure that all the documents support the same explanation and allow the AEAT—or, later, a Spanish economic-administrative tribunal—to verify the correct tax result.
In the proceedings considered here, four groups of documents were particularly relevant.
- All invoices issued during the fourth quarter of 2023. These made it possible to verify individually the transactions included in the disputed period.
- A list of all invoices issued in 2023, organised by quarter. This helped separate Q4 from the other periods and identify any duplicated, omitted or incorrectly allocated transaction.
- An annual list of orders organised by month. This allowed the invoices to be connected with the sales that had actually been processed.
- A specific invoice summary for Q4. It showed the taxable amount of €7,716.64 and facilitated reconciliation with the individual invoices and orders.
The company also submitted an electronically signed explanation from the accountant who prepared the OSS VAT return, together with an extract illustrating the mistake and a Spanish translation. That statement explained how the error arose. Its evidential value was strengthened because the explanation was supported by the underlying transactional documents.
Consistency between the evidence, the figures and your explanation
The AEAT may question a correction if it finds differences between your allegations, invoices and accounting records. You should therefore prepare a clear reconciliation showing how many invoices exist, the amount of each invoice, which orders support them and how the final total is calculated.
If your documents use different expressions for taxable amount, revenue and total including VAT, explain those terms carefully. In this case, there were three separate figures: a taxable amount of €7,716.64, VAT of €1,620.50 and a gross total of €9,337.14. Confusing any of these amounts may give the Spanish Tax Agency a reason to argue that the correction remains unclear.
What matters is whether a person outside your business can reproduce the calculation without making assumptions. If the figure can be verified directly from the documents submitted, you will have a much stronger evidential basis for appealing the Spanish VAT assessment.
Can you submit additional evidence when appealing the AEAT assessment?
A further issue is the stage at which the documents were submitted. Part of the evidence was provided with the recurso de reposición, after the initial Spanish tax review had ended. The AEAT should not automatically disregard relevant evidence merely because it was not submitted during the first phase.
The written allegations rely on the Spanish Supreme Court judgment of 20 April 2017, ROJ STS 1509/2017. The judgment considered whether evidence not previously submitted during the tax management procedure could be examined at the administrative review stage.
«The documents attached to the administrative reconsideration appeal should be assessed and taken into account».
This reasoning is directly relevant to an OSS VAT return error in Spain. If you submit invoices, orders and accounting records with your appeal and those documents make it possible to verify the correct amount, the dispute should not be closed simply because the evidence was produced later. The Spanish tax authorities must examine it and give reasons for their conclusion.
This does not mean that every document submitted on appeal will automatically result in cancellation of the assessment. The evidence must be relevant, readable and internally consistent. You should also explain what each document proves. Sending numerous files without an index or reconciliation may make the evidence difficult to understand.
If the AEAT claims that you did not explain the cause of the error even though you provided a signed explanation and matching transactional records, your appeal should identify that contradiction precisely. It is not enough to state that the Spanish Tax Agency is wrong. You should specify which evidence it failed to assess, what fact that evidence establishes and what VAT result follows from it.
How do you appeal an OSS VAT assessment issued in Spain?
If you have already received an AEAT assessment, start by checking the notification date and the procedural stage of the case. Spanish tax appeal deadlines are strict, and the correct response will depend on the decision you have received and whether an earlier appeal has already been filed.
In the case considered here, the company first filed a recurso de reposición. It subsequently lodged an economic-administrative claim before Spain’s Central Economic-Administrative Tribunal, the Tribunal Económico-Administrativo Central or TEAC. During that procedure, the company was given access to the file and a period in which to submit written allegations and propose evidence.
The allegations were signed in Lithuania, illustrating a common feature of OSS disputes: the affected company may be located outside Spain while the appeal must be conducted under Spanish tax procedure and before Spanish reviewing bodies.
You should then reconstruct the disputed quarter independently from the incorrect return. Use the original invoices, orders and accounting records. Prepare a summary showing the gross amount, taxable amount, VAT rate and VAT due. Finally, compare that result with the figure actually entered in Spain’s Form 369.
- Identify the exact incorrect figure and the field in which it was entered.
- Explain specifically how the mistake occurred.
- Match the invoices with the orders and the quarterly summary.
- Check that the calculations reconcile and do not mix net and gross amounts.
- State in the appeal which document proves each relevant fact.
- Identify any evidence that the AEAT has ignored or answered only generically.
Avoid sending only a table created after the error, submitting hundreds of unindexed files or assuming that the disproportionate figure will be enough for the AEAT to correct the return. The larger the Spanish tax assessment, the more important it is to provide an organised and verifiable explanation.
Speak to a tax lawyer in Spain about your OSS VAT assessment
SAEZ.LAW is a Spanish tax litigation firm that assists businesses and non-resident taxpayers in disputes with the Spanish Tax Agency. Álvaro Sáez can review the assessment, the available evidence and the appropriate appeal strategy in Spain.
If the OSS error is proved, the Spanish assessment should be recalculated
The conclusion is clear: the Spanish Tax Agency should not maintain an assessment based on an incorrect amount without properly examining the evidence that establishes the actual transactions. In this case, the Q4 invoices, annual records, orders and the accountant’s explanation all led to the same result: a taxable amount of €7,716.64, VAT of €1,620.50 and a gross total of €9,337.14.
Once that documentation is in the Spanish tax file, the purpose of the appeal is to ensure that it is assessed as a whole and that the liability is recalculated using the correct figures. If the decision merely denies the existence of the error without addressing the evidence submitted, there may be serious grounds for challenging it.
If your company is established outside Spain but has received an OSS VAT assessment from the AEAT, do not assume that the distance or the cross-border nature of the case prevents you from appealing. A Spanish tax lawyer can review the notification, procedural deadlines and evidence and represent your position before the relevant Spanish tax bodies.
Do not wait for the problem to resolve itself. Check the deadline, organise the supporting documents and determine the appropriate Spanish appeal procedure before the assessment moves to the next enforcement stage.