Iñaki Beltrán lives in Logroño and shares with his wife, Nerea, a securities account at a Portuguese bank that they opened when they were working in Porto. In September 2026 he receives a letter from the Agencia Tributaria, the Spanish tax agency: it tells him that, according to data received from another country, in 2024 he received 7,400 € of dividends that do not appear on his return, and it "invites him to review" his position. There is no file number and no deadline. Iñaki reads the figure, works out 23 % in his head and believes he owes more than 1,700 €, plus a fine. Both things are wrong.
No, a letter like this is not a formal request (requerimiento). And that difference is what decides whether you will pay a surcharge or a penalty.
Why the law does not treat it as a request
Article 27.1 of the General Tax Act (Ley General Tributaria) treats as a prior request any administrative action carried out with the formal knowledge of the taxpayer and aimed at the acknowledgement, regularisation, review, inspection, securing or assessment of the tax debt. A letter that reports a piece of data and leaves the initiative to the taxpayer does not start any procedure or require anything of you. As long as that is all you have, if you file the corrected return yourself, what applies is the surcharge of article 27, and article 179.3 rules out liability for an infringement.
How to recognise each kind of paper, with the signs on the document itself, is covered in the difference between an information letter and a formal request. This page is about something else: what to do in the weeks after receiving it.
First, rule out that there is anything more
The paper letter may not be the only thing. Before calculating anything, Iñaki should log in to the agency's online office and check two separate places: the notifications section and the communications section. If either of them shows a document with a file number, a deadline in working days or the word "requerimiento", the situation changes. If there is only the letter, the window is still open.
It is also worth checking the Dirección Electrónica Habilitada, the official electronic address for notifications, if it was ever activated. Where electronic notification is compulsory or was chosen, article 43.2 of Law 39/2015 treats it as refused if ten calendar days pass without it being opened, and the procedure goes ahead: a request deposited there may have closed the door without the taxpayer knowing. That risk is dealt with in I have been notified and did not notice.
The figure in the letter is not what you owe
The letter refers to gross income. What is paid is something else, and in Iñaki's case the gap is huge:
| Step | What is done | Result |
|---|---|---|
| Figure in the letter | Gross 2024 dividends attributed to Iñaki | 7,400 € |
| Actual ownership | The account belongs to both spouses at 50 % | 3,700 € each |
| Spanish tax | 3,700 € at 19 %, the first savings band | 703 € |
| Tax paid in Portugal | Withholding at source according to his statement, half each | 555 € |
| Double taxation relief | The lower of the tax paid abroad and the Spanish tax on that income | 555 € |
| Tax Iñaki has to pay | 703 − 555 | 148 € |
Article 80 of the IRPF Act, the law on Spanish personal income tax, allows tax paid abroad to be deducted, up to the amount that income bears in Spain. If more was withheld at source than the tax treaty allows, the excess is not recovered in the Spanish return: it would have to be claimed in the other country, with the adviser the client has there. The guide on international double taxation relief explains the limit in more detail.
And the same adjustment applies to Nerea, who has not received a letter but holds the other half. Filing only Iñaki's would leave his wife with 3,700 € undeclared and the data already in the hands of Hacienda, as the tax office is commonly known.
The surcharge, calculated with dates
The 2024 income tax return had to be filed by 30 June 2025. If Iñaki files the supplementary return in October 2026, more than twelve months have passed, so article 27.2 sets a surcharge of 15 % plus late-payment interest from the end of those twelve months:
- Tax on the supplementary return: 148 €.
- 15 % surcharge: 22.20 €.
- 25 % reduction under article 27.5, if he pays the tax on filing and pays the surcharge within the period of its assessment: 16.65 €.
- Late-payment interest for about three months on 148 €: a few euros.
By contrast, if a formal request reached him before he filed and Hacienda assessed those 148 €, the infringement under article 191 would be minor, with a fine of 50 % of the amount not paid. In this particular case the penalty would also be small, but it would leave a record that article 187 takes into account if there is another infringement of the same kind in the following four years. And in cases with larger amounts of tax, the difference is measured in thousands of euros.
If the 2024 data has arrived through automatic exchange, the 2023 and 2025 data will normally exist too. The letter mentions one year; the regularisation should look at every year still open. Correcting only the one mentioned leaves the others exposed with the same pattern.
The neighbouring years
Iñaki received dividends from the same bank every year. As at September 2026, each tax year is in a different position:
| Tax year | End of the filing period | Status | Surcharge if filed in October 2026 |
|---|---|---|---|
| 2021 | 30 June 2022 | Time-barred since July 2026 | Nothing to file |
| 2022 | 30 June 2023 | Open until summer 2027 | 15 % plus interest |
| 2023 | Early July 2024 | Open | 15 % plus interest |
| 2025 | 30 June 2026 | Open | 3 %, no interest |
The 2025 row is the one that usually surprises people: a return filed three months ago already carries a surcharge if something was missing from it, however small. Filing the supplementary returns in order, from the oldest to the most recent, avoids mistakes when carrying data from one year to the next.
If you have a similar letter and want to know which years need to be touched and what it amounts to, you can send it with the returns you filed through the regularisation form.
If the figure in the letter is wrong
Not every letter is right. Sometimes they attribute 100 % of a joint account to a single holder, repeat an amount or count as income a transfer between the taxpayer's own accounts. If the data is wrong, there is nothing to regularise for that part. The sensible course is to keep the documents that prove it (statements, the account agreement, the bank's tax certificates) and file the supplementary return only for what is genuinely missing.
What is not advisable is to correct the error by filing a return that does not match any document. If Hacienda later compares the letter, the supplementary return and the data from the other country, any unexplained difference is what will open a review.
Other obligations the same letter brings to light
If the balance of that account exceeded 50,000 € on 31 December, or the average balance for the last quarter did, Iñaki and Nerea may have been required to file Modelo 720, the return on assets held abroad. It is an information return, and its penalty regime changed after the judgment of the Court of Justice of the European Union of 27 January 2022; today, filing late without a prior request is governed by the general rule for information returns. It is summarised in Modelo 720 penalties after the judgment.
Regularising income that Hacienda already knows about, or is going to know about, is the work of the voluntary disclosure service at Salama Tax, which explains which documents are requested and how each tax year is quoted.