Filed late without a letter: the 1 %-a-month surcharge, and what changes when Hacienda writes first

A restaurant owner in Corralejo comes back from August and finds the second-quarter IGIC return still unfiled: 3,000 euros that should have been paid by 20 July. A German landlord in Costa Calma realises in October that his 2025 income-tax return never went in. A small SL in Puerto del Rosario forgot the quarterly withholding return for its two employees. The three of them have the same question, and the answer depends on one fact only: who moves first. If you file before the tax office writes to you, you pay a surcharge that starts at 1 % and grows by one point a month, with no penalty and, for a year, no interest. If the tax office writes first, the same 3,000 euros carry a penalty that starts at 50 %, plus interest from the day the deadline passed. This piece sets out both roads as the Ley General Tributaria writes them in 2026, works the numbers on that IGIC quarter, and explains why the letters arrive faster than they used to. Quotations are in Spanish with the reading in English.

One line divides the two roads: the requerimiento previo

The Ley 58/2003 — the General Tax Law that governs every Spanish tax administration, the Agencia Tributaria Canaria included (art. 1) — keeps two separate regimes for a return filed late. Which one applies turns on whether there was a «requerimiento previo», and the law defines it broadly:

«se considera requerimiento previo cualquier actuación administrativa realizada con conocimiento formal del obligado tributario conducente al reconocimiento, regularización, comprobación, inspección, aseguramiento o liquidación de la deuda tributaria» — any administrative action, carried out with the taxpayer's formal knowledge, aimed at recognising, regularising, checking, inspecting, securing or assessing the tax debt counts as a prior requirement (art. 27.1).

A notice opening a data-verification procedure, a limited check or an inspection is a requirement; so is a proposed assessment. What matters is the formal knowledge — the notification, which for companies, the self-employed on the electronic system and anyone who has opted in arrives in the electronic mailbox and is deemed delivered ten days after it is posted there, as we explained in our piece on Hacienda's electronic notifications. The agency also sends information letters that open no procedure — in practice they are not a requirement in this sense — but the only safe way to read any letter is to act the day it arrives, because once a formal action exists the first road closes.

The law rewards the taxpayer who moves first in two places. Article 179.3 says that those who «voluntariamente regularicen su situación tributaria» — voluntarily regularise their tax position — «no incurrirán en responsabilidad por las infracciones tributarias cometidas» — incur no liability for the infringements committed. And article 191, the infringement of failing to pay what a correct self-assessment would have shown, excludes from its own scope the case where the taxpayer «se regularice con arreglo al artículo 27» — regularises under article 27. Filing first is not a mitigating circumstance; it takes the penalty off the table.

Road one: you file first — the surcharge ladder

Since the Ley 11/2021 the surcharge for a late return filed without a requirement is a single ladder:

«El recargo será un porcentaje igual al 1 por ciento más otro 1 por ciento adicional por cada mes completo de retraso con que se presente la autoliquidación o declaración respecto al término del plazo establecido para la presentación e ingreso» — the surcharge is a percentage equal to 1 % plus a further 1 % for each complete month of delay with which the return is filed after the end of the filing and payment period (art. 27.2).

So a return filed within the first month carries 1 %; one full month plus a day carries 2 %; eleven full months and a day carry 12 %. The surcharge is calculated on the amount to pay and «excluirá las sanciones que hubieran podido exigirse y los intereses de demora devengados hasta la presentación» — it excludes the penalties that could have been imposed and the late-payment interest accrued up to filing. After twelve months the ladder stops: the surcharge is 15 %, still without penalty, but «se exigirán los intereses de demora por el período transcurrido desde el día siguiente al término de los 12 meses» — interest is charged for the period from the day after the twelve months end until the return is filed. The rate is the one the budget law sets: 4.0625 % a year, fixed by the 2023 budget and still applied under the extended budgets in 2026 (art. 26.6 and Ley 31/2022, DA 42ª).

Two conditions keep you on this road. The late return «deberán identificar expresamente el período impositivo de liquidación al que se refieren y deberán contener únicamente los datos relativos a dicho período» — must expressly identify the tax period it refers to and contain only that period's data (art. 27.4): the forgotten quarter goes in its own return, never folded into the next one. Folding it in is what turns a surcharge into a penalty — a light one by law, but a penalty (art. 191.6). And you pay, or ask to defer, when you file: if you file late and do not pay and do not request a deferral, the surcharge is charged and the executive-period surcharges are added on top (art. 27.3).

The surcharge is not something you add to the return. The tax office assesses it afterwards and notifies it — a proposal, a hearing period, an assessment — and the assessment opens a payment window that runs to the 20th of the following month if notified in the first half of a month, or to the 5th of the second month if notified in the second half (art. 62.2). That window is where the last piece sits: the surcharge «se reducirá en el 25 por ciento» — is reduced by 25 % — provided the reduced surcharge is paid within that window and the tax itself was paid when the return was filed, or deferred with a bank guarantee requested at filing (art. 27.5). The reduction is lost, and re-charged, if either payment slips.

The ladder in numbers: a 3,000-euro IGIC quarter

Take the Corralejo restaurant: the second-quarter Modelo 420 was due by 20 July 2026, and the amount to pay is 3,000 euros. The Agencia Tributaria Canaria applies the same article 27, because the General Tax Law governs it.

• Filed on 5 August 2026, sixteen days late: no complete month, so 1 % — 30 euros, reduced to 22.50 if the surcharge assessment is paid in its window. No penalty, no interest.
• Filed on 30 September 2026, two complete months and ten days late: 3 % — 90 euros, reduced to 67.50. No penalty, no interest.
• Filed on 15 January 2027, five complete months late: 6 % — 180 euros, reduced to 135.
• Filed on 20 September 2027, fourteen months late: 15 % — 450 euros, reduced to 337.50 — plus interest at 4.0625 % on the 3,000 euros for the 62 days from 21 July 2027 to filing, about 20.70 euros. Still no penalty.

Now the other road. The restaurant does nothing, and in October the Canary agency's data-verification notice arrives, because the quarter's sales were reported by its card terminal and by its customers' and suppliers' annual returns. The amount not paid is 3,000 euros, there was no concealment, so the infringement is light and the penalty is 50 % (art. 191.2): 1,500 euros. If the owner accepts the assessment without appealing, the penalty falls by 30 % for conformity to 1,050 euros (art. 188.1.b); if it is then paid within its window without any appeal, by a further 40 % to 630 euros (art. 188.3). Interest runs from 21 July 2026 to payment — for a payment on 30 September, 72 days, about 24 euros. The bill for the same forgotten quarter: 654 euros against 67.50, nearly ten times more, and the 630 is the best case, on the assumption that nothing is contested.

Change one fact and the gap widens. A 9,000-euro quarter omitted entirely, with concealment, is a serious infringement: the minimum 50 % rises with the economic harm — an omission above 75 % of what was due adds 25 points (art. 187.1.b) — to 75 %, or 6,750 euros, reduced by conformity and prompt payment to 2,835. The same 9,000 euros filed late on the taxpayer's own initiative after two months would carry 270 euros of surcharge, 202.50 after the reduction.

Road two: what the letter turns into

Once a requirement exists, the late payment is no longer a surcharge matter but an infringement under article 191, and the law grades it in three steps. It is «leve» when the amount not paid is 3,000 euros or less, or more without concealment — a proportional fine of 50 %. It is «grave» when the base exceeds 3,000 euros and there was concealment, or whatever the amount when false invoices were used or the books were kept incorrectly in more than 10 % of the base, or when withheld amounts were kept — 50 % to 100 %, the minimum raised by the repeated-infringement criterion (5, 15 or 25 points) and by the economic-harm criterion (10 to 25 points) of article 187. It is «muy grave», 100 % to 150 %, when fraudulent means were used or more than half of the base was tax withheld from others and kept. Withholdings — the Modelo 111 the Puerto del Rosario SL forgot — are the one category the law never treats as light.

The reductions are the same for every grade and they stack. Accepting the assessment — not appealing it — takes 30 % off (65 % for the negotiated «actas con acuerdo» of an inspection); paying the remaining penalty within its window, without appealing either the assessment or the penalty, takes a further 40 % off the reduced figure (art. 188). Both are conditional: appeal later and the reduction is charged back «sin más requisito que la notificación al interesado» — with no formality beyond a notice. Interest at 4.0625 % runs on the tax from the day after the original deadline, whatever happens to the penalty (art. 26).

Why the letters arrive faster in 2026

The requirement that closes the first road is generated, more and more, by data that reaches the tax offices before you file. Since January 2026 banks and payment institutions report account movements on the Modelo 196 monthly rather than yearly, and the reporting perimeter now includes payment and electronic-money entities — the Bizum channel — as we set out in our piece on Hacienda's overnight bank freezes. Since 2024 the platforms report every holiday-let seller's quarterly takings on the Modelo 238, net of their fees, as our DAC7 piece explains. Card terminals, the customers' and suppliers' annual returns and, from 2027, the electronic invoice close the rest of the circle. The data-verification procedure of article 131 opens precisely «cuando los datos declarados no coincidan con los contenidos en otras declaraciones presentadas por el mismo obligado o con los que obren en poder de la Administración tributaria» — when the declared data do not match other returns or the data the Administration holds — and a return that was never filed is the simplest mismatch of all. The window in which filing first is still possible has not changed in law; in practice it is shorter every year.

The returns with nothing to pay

Not every late return carries an amount, and the law has a separate scale for those. Failing to file a return in time «sin que se haya producido o no se pueda producir perjuicio económico» — where no economic harm to the Treasury is or can be caused — is a light infringement with a fixed fine of 200 euros, or 400 for the census declarations 036 and 037 (art. 198.1). For the information returns — the 347, the 349, the 190, the 180, the 720 — the fine is 20 euros for each item of data or set of data about one person, with a minimum of 300 and a maximum of 20,000 euros. Here too the law halves everything for the taxpayer who moves first: «si las autoliquidaciones o declaraciones se presentan fuera de plazo sin requerimiento previo de la Administración tributaria, la sanción y los límites mínimo y máximo serán la mitad» — if the return is filed late without a prior requirement, the fine and the minimum and maximum are halved (art. 198.2): 100 euros, 200 for a census form, 10 euros per item between 150 and 10,000 for an information return. Since 2022 the foreign-assets return, the Modelo 720, carries these general fines and nothing more. A return filed in time but incompletely, and corrected later on your own initiative, is treated under the same halved scale for what was added late, not under the 150-euro fine for incorrect returns of article 199.

Filing late and paying later: two clocks, not one

The surcharge ladder counts the delay in filing. Payment has its own clock. A self-assessment filed without payment enters the executive period the day after the filing deadline or, if that has already passed, the day after it is filed (art. 161.1.b), and the executive period carries its own surcharges on the whole unpaid debt: 5 % if you pay in full before the enforcement order is notified, 10 % if you pay the debt and the surcharge within the order's window, 20 % plus interest after that (art. 28). A deferral or instalment request filed with the late return stops the executive period from opening while it is processed (art. 161.2), and for debts up to 50,000 euros the request needs no guarantee; interest still accrues on the deferred amount (art. 65.5), and the 25 % reduction of the surcharge survives only when the deferral is secured by a bank guarantee or surety insurance requested at filing (art. 27.5). The rule of thumb is simple: file the forgotten period in its own return, pay it or ask to defer it in the same act, and let the surcharge assessment come.

One more rule, added in 2021, is worth knowing after a check. If the tax office regularises a period — say, the 2023 rental income of the Costa Calma landlord — and within six months of that assessment being notified you file the other periods of the same tax with the same facts, pay them in full, appeal nothing and no penalty was imposed in the check, «no se exigirán los recargos» — no surcharge is charged on those returns (art. 27.2, last paragraphs). Break any of the four conditions and the surcharge is charged by simple notice.

What we do

We file the forgotten period the day you call — in its own return, with the payment or the deferral request in the same act — so that the ladder stops climbing and no letter can close the road; we check the surcharge assessment when it arrives and pay it inside the 25 % window; and where a requirement has already been notified, we run the conformity and prompt-payment reductions and the appeal decision with the numbers in front of you. The tax advisory page describes the service, the autumn tax calendar carries the dates that matter next, and a first meeting is booked online.

Common questions

I forgot the second-quarter IGIC return. What do I pay if I file today?

If no letter has arrived, the surcharge of article 27: 1 % of the amount plus 1 % for each complete month since 20 July, no penalty and no interest during the first twelve months, and 25 % off the surcharge if you pay the tax when you file and the surcharge assessment within its window. On 3,000 euros filed on 30 September that is 90 euros, reduced to 67.50. File the quarter in its own Modelo 420 and pay it or request a deferral in the same act.

Is every letter from Hacienda a requerimiento previo?

A requirement is any action carried out with your formal knowledge aimed at checking or assessing the debt — the opening of a data verification, a limited check or an inspection, or a proposed assessment. Pure information letters open no procedure and are, in practice, not a requirement. But the notification counts from the day it is deemed delivered, ten days after it is posted to your electronic mailbox, so a letter you have not read can already have closed the first road: file on the day any letter arrives and check its nature afterwards.

Can the penalty be reduced once a requirement has arrived?

Yes, twice. Accepting the assessment without appeal reduces the penalty by 30 %, and paying what remains within the payment window without appealing anything reduces it by a further 40 %: a 1,500-euro penalty becomes 630. Both reductions are cancelled if you appeal later. Interest on the tax from the original deadline is charged in every case.

What if the late return has nothing to pay — a 347, a 349 or a Modelo 720?

Then the fixed fines of article 198 apply: 200 euros for a return with no amount, 400 for a census form, and 20 euros per item of data with a minimum of 300 for information returns. Filing late on your own initiative halves all of them — 100, 200, and 10 euros per item between 150 and 10,000. The Modelo 720 carries these general fines since 2022.

Facts verified in September 2026 (General Tax Law, Ley 58/2003, articles 1, 26, 27, 28, 62, 65, 131, 161, 179, 187, 188, 191, 198 and 199 in the text in force after Ley 11/2021; the late-payment interest of 4.0625 % under the 2023 budget law's additional provision 42, applied under the extended budgets; the tax agency's manual on late-filing surcharges and its procedure GZ71). The surcharge and penalty percentages are those of the law in force at publication; the interest rate changes with each budget law, and the examples assume a debt paid in full at filing and no appeal.