Lucía Ferrer owns a flat she inherited in the Cabanyal district of Valencia, which she let to tourists through online platforms during the summer of 2024. She received 9,400 € and did not include it in her income tax return, because her adviser at the time told her that "you only declare that once it goes over a certain figure". In September 2026 she receives a communication from the Agencia Tributaria, the Spanish tax agency: it tells her that a platform has reported income in her name and reminds her that she can review her return. In the spring her brother received another letter, almost identical in appearance, which gave him ten days to provide contracts and receipts. Lucía wants to know whether she is in the same position as he is. She is not, and the difference is worth money.
Two pieces of paper with the same letterhead and opposite effects
The Agencia Tributaria uses the same paper, the same online portal and similar language for things that are legally very different. A notice letter (the Agency also calls them information or campaign communications) does not open any procedure. It tells you what it knows and invites you to act. A formal request (requerimiento), on the other hand, forms part of a procedure that has already started, or starts one: it demands that you provide something, within a deadline, under a case number.
What is at stake is not the form but the consequence. While all you have is a notice, you can correct your return on your own initiative, and what you pay is a surcharge. Once there is a formal request about that tax and that year, spontaneous correction is no longer available on those terms, and what opens up instead is the door to a penalty.
The sentence in article 27 that decides which side you are on
Article 27.1 of the Ley General Tributaria, Spain's General Tax Law, governs the surcharges for filing late "without a prior request". And it defines that request broadly: it is "any administrative action carried out with the formal knowledge of the taxpayer leading to the recognition, regularisation, verification, inspection, securing or assessment of the tax debt".
Two requirements follow from this, and they are worth reading separately:
- Formal knowledge. The action must have been notified to you. Whatever Hacienda, as the Spanish tax office is commonly called, does internally, cross-checking data or preparing a proposal, does not count until it reaches you.
- Aimed at regularising your debt. It must be directed at verifying or assessing your obligation. A letter that only informs you and leaves the initiative with you does not meet this second condition.
The guide on what counts as a prior request goes through the doubtful cases one by one. Here what matters is the practical test for reading the piece of paper in front of you.
Signs you can read in the document itself
| What you see in the letter | Usually points to a notice | Usually points to a formal request |
|---|---|---|
| Deadline to reply | None, or only a guide | A specific deadline, normally in working days |
| Reference | Generic or campaign reference | A case number and the body handling it |
| Main verb | "We inform you", "you may review" | "You must provide", "you are required to" |
| Procedure cited | None | Limited verification, data verification, a request under art. 93 |
| Warnings | An invitation to correct | Possible penalties for not complying |
| Appeals footer | Usually absent | Sometimes states that no separate appeal lies against the step |
The table is only a guide: what counts is the content, not the label. There are letters headed "communication" that in fact start a procedure, and the other way round. If the document mentions the start of a limited verification procedure, you are dealing with a formal request, however friendly the tone.
Lucía's figures on either side of the line
Let us suppose, purely as an example, that once the 9,400 € is added and the deductible expenses are taken off, Lucía's 2024 income tax comes out at 2,350 € more. The deadline for that return ended on 30 June 2025, so by October 2026 more than twelve months have passed.
If she puts it right herself, with the notice in her hand:
- The surcharge in article 27.2: as more than twelve months have passed, 15 % of the amount payable: 2,350 × 15 % = 352.50 €.
- If she pays the tax when she files and the surcharge within its deadline, the surcharge is reduced by 25 % (article 27.5): 352.50 × 0.75 = 264.38 €.
- On top of that comes late-payment interest from the end of those twelve months, which article 27.2 itself provides for this band.
- There is no penalty: the surcharge "will exclude the penalties that might have been imposed".
If she waits and a formal request arrives:
- Hacienda assesses the same tax, 2,350 €, with late-payment interest.
- It opens penalty proceedings under article 191. With a base below 3,000 €, the offence would be minor, with a fine of 50 %: 1,175 €.
- With the 30 % reduction for agreement under article 188.1.b): 822.50 €.
- With the further 40 % reduction for paying on time without appealing under article 188.3: 493.50 €.
Even in the best penalty scenario, Lucía pays almost twice as much as she would by putting things right herself, and she is also left with a record that weighs on how any future penalties are graded. The general comparison between the two paths is in surcharge against penalty, and the detailed month-by-month calculation of the surcharge in calculating the article 27 surcharge.
A notice letter freezes nothing. If, while you are deciding, a formal request arrives about the same tax and the same year, spontaneous correction no longer works on those terms. There is no published period between one and the other: it may be a year or it may be weeks.
The brother's case: when a formal request already exists
The letter Lucía's brother received, with ten days to provide documents and a case number, was almost certainly the start of a limited verification procedure. From that point on, filing a supplementary return does not wipe out the procedure. Article 87.5 of the Regulations on tax management and inspection (Royal Decree 1065/2007) provides that returns you file for that tax and period once the proceedings have started do not have their ordinary effects: they are taken into account within the procedure, not as a voluntary correction.
That does not mean there is nothing to be done. It means the ground has changed: the task now is to reply properly, within the scope set by the communication, and to prepare the defence against the proposal. What to answer and what not to is developed in the guide what you answer and what you do not, and the real deadlines in how many days you really have to reply.
If you have a letter and do not know which side you are on, you can send it through the letter-from-Hacienda form together with the return for the year concerned. With the complete document, including the footer and the reference, the type of action can be identified.
Grey areas best not taken as settled
There are situations where the answer is not immediate:
- A formal request about another year. The prior request has to refer to the same tax and period. One about the 2023 income tax return does not, in principle, prevent you from correcting 2024 with a surcharge; but if the facts are the same, the order should be decided with care. The guide on the order for correcting several years deals with this problem.
- A request for information about third parties. If you are asked for details of your tenant or a client, the action is not directed at your debt, although what you reply may end up being used to check you.
- A procedure that has lapsed. Article 104.5 of the General Tax Law states that the actions of a lapsed procedure are not treated as requests for the purposes of article 27. If an earlier procedure ended because it lapsed, the possibility of correcting with a surcharge is restored, with the warning that the authorities can open another one as long as the limitation period has not run out.
- Letters from other authorities. A letter from the regional government or the town hall about one of its own taxes is not a request for the purposes of your income tax.
In all these cases the conclusion depends on the specific wording and the dates, and no reading is free of risk. The prudent course is not to file anything until you have identified precisely what has been notified and what it concerns.
What not to do with a notice letter
Putting it away in a drawer is the most expensive mistake, but not the only one. Nor is it advisable to answer a notice letter as if it were a formal request, sending documents or explanations through the official registry: there is no procedure for them to be added to, and whatever you send stays in the hands of the authorities. The useful answer to a notice is, where appropriate, the corrected return.
And the other years should be reviewed. If Lucía also let the flat in 2025, the same information will arrive next year. Correcting only the year of the notice leaves the next one exposed to the same problem, with the difference that by then Hacienda already knows the pattern exists. The relationship between surcharge, interest and penalty, in general terms, is also explained in the difference between a surcharge and a penalty.
Reading communications from the Agencia Tributaria, deciding whether to correct or wait, and replying to formal requests are part of the Salama Tax service for letters from Hacienda, which describes the paperwork worth gathering in each case.