Regularising one year, in Spanish terms bringing it up to date voluntarily before the tax office asks, is a formality. Regularising five is a project, and the order in which things are done changes the result: which years are still open, which ones carry figures forward from earlier years, which information returns have to be filed even though they carry no tax, and beyond what figure the conversation stops being about tax. This guide is the script we follow ourselves, in that order.
Step one: an inventory, by tax and by year
Before calculating anything you need to know exactly what is missing. "I did not declare the rents" is no use; what is useful is a table with one row for each combination of tax and period, because each box has its own deadline, its own limitation period and its own surcharge.
| Tax | Period | What is missing | Is tax payable? |
|---|---|---|---|
| IRPF (personal income tax) | 2022 | Rental income from property | Yes |
| IRPF | 2023 | The same, plus a gain on the sale of shares | Yes |
| Modelo 720 | 2022 | Foreign account never declared | No |
| VAT (IVA) | 2023, Q4 | Quarterly self-assessment not filed | Yes |
| Wealth tax | 2023 | Not filed despite exceeding the threshold | No |
That table is the file. Everything that follows is decided on the basis of it.
Step two: which years are still open
The tax authorities' right to assess tax becomes time-barred four years after the day following the end of the statutory filing period. Time-barred years are not regularised: filing a self-assessment for a dead year brings it back to life, because that act interrupts the limitation period and reopens the door to a review. The detail (when the count starts, what restarts the clock, which cases have different periods) is in the limitation period and what interrupts it.
Some items carry their effect forward: a negative taxable base, a deduction still to be used, the acquisition value of an asset not yet sold. The tax authorities can review those items beyond the four years when they have effects in years that are still open. Treating an old year as closed because it is time-barred, without checking what it carries forward, is the mistake that produces the most surprises.
Step three: identify the linked years
Some figures do not live in a single year. If they are corrected in one, they have to be corrected in all the following ones, or the file becomes inconsistent, and inconsistency is the first thing an automated cross-check picks up.
- Depreciation on a let property. If you start deducting it in 2022, the same approach has to be kept in 2023, 2024 and 2025, and the accumulated depreciation comes off the acquisition value when the property is sold.
- Negative taxable bases and capital losses waiting to be offset. They are carried forward over several years: changing the first changes all the later ones.
- VAT credits carried forward. A corrected quarter shifts the balance of every quarter after it.
- Acquisition value of assets. An inheritance declared at one value and a later sale calculated on another cannot both stand.
That is why the filing order always runs from the oldest year to the most recent: each one is calculated with the figures of the previous year already corrected.
Step four: information returns get filed too
Information returns carry no tax, so they generate no article 27 surcharge, the recargo for late filing, which is calculated on an amount payable that does not exist here. What they do generate is a penalty for late filing, halved when the return is filed without a prior request. That reduction is the whole advantage of moving first, and it is substantial.
| Information return | What it declares | Ordinary deadline |
|---|---|---|
| Modelo 720 | Accounts, securities, insurance and real estate abroad | First quarter of the following year |
| Modelo 721 | Crypto-assets held abroad | First quarter of the following year |
| Modelo 714 | Wealth tax, where there is no tax to pay but there is an obligation to file | That of the income tax campaign |
Modelo 720 also has a history of its own: the specific penalty regime that came with it was struck down, and today the general regime applies, which completely changes the arithmetic of regularising back years. It is told in the penalty regime today, and how the form works is on its own page.
Step five: check the threshold before filing
The Spanish Criminal Code places the line for the offence of tax fraud at 120,000 euros of tax evaded, for each year and for each tax. Below that, the matter is administrative. Above it, it stops being a question of surcharges and penalties. The criminal law itself provides that a complete regularisation of the tax position, carried out before notice is given that a review has started or before a criminal complaint is filed, removes criminal liability, which is why the date of filing matters so much. We never make that calculation roughly: it is done year by year and tax by tax, before anything is touched.
The practical consequence is that the inventory from step one has to be priced in euros before the strategy is chosen. If any box comes close to that figure, the order of work changes, and so does the urgency. Nothing is improvised here and nothing is guaranteed: the exposure is explained and the decision is taken together with the client.
Step six: the money
Regularising five years at once produces a debt that is rarely paid in one go. The options are not endless:
- Pay on filing. This keeps the 25 % reduction of the surcharge intact.
- Defer or pay in instalments. The surcharge reduction is kept only if the application comes with a joint and several guarantee from a credit institution or a surety insurance certificate. With a different guarantee, or none, the reduction is lost.
- Stagger the filings to spread the effort. This is the worst option: every month that passes raises the surcharge on the year still pending and multiplies the risk of a formal request arriving that turns everything into a penalty.
The full calculation, with the effect of each option, is in how the surcharge is worked out, month by month.
Supplementary return or rectification: choose correctly
Not everything that is corrected goes down the same road, and getting it wrong delays the file by months.
| If the result is… | Route | Effect |
|---|---|---|
| A higher amount payable, or a lower refund | Supplementary self-assessment (complementaria) | Filed and paid; it generates the article 27 surcharge |
| A lower amount payable, or a higher refund | Request for rectification of the self-assessment | Opens a procedure; the tax authorities decide |
The supplementary return is made by the taxpayer and takes effect when it is filed. Rectification is a request: it has to be reasoned, accompanied by evidence, and you wait for a decision, which may be a refusal. The reform that introduced the corrective self-assessment is unifying both routes form by form, so before deciding it is worth checking whether the specific form for the year being corrected already allows it.
Within a multi-year regularisation it is common for both to coexist: one year in which too little was paid and another in which too little was deducted. They are filed at the same time, but by different routes, and the second does not offset the first: there is no informal set-off between years.
Step seven: file as a block and document it
When everything has been calculated, the filing is done in one go and in chronological order, on the same day if possible. There are three reasons. First, a partial regularisation exposes the rest and acts as a warning. Second, the consistency between years can only be seen if they arrive together. And third, any action by the tax authorities notified in the middle closes the window for whatever is left.
Alongside the self-assessments, it is worth preparing and keeping the internal file: origin of funds, statements, contracts, foreign certificates and the calculation workbook. It is not submitted unless asked for (what to answer and what not to is in its own guide), but having it ready is the difference between replying in fifteen days and asking for more time.
What is not regularised by filing forms
Some situations are not fixed with a late self-assessment, because the problem is not in the form. A wrong tax address is corrected in the census of taxpayers, not in the income tax return; a business registration that was never made is notified on Modelo 036 (Modelo 037 was abolished by Orden HAC/1526/2024, with effect from 3 February 2025); a registered obligation that is still live but no longer applies has to be cancelled, or the tax office will keep expecting quarterly returns. Those pieces are put in order before or at the same time as the self-assessments, because if the census says one thing and the forms say another, the file is born contradicting itself.
What we do with a file like this
We draw up the inventory, mark what is time-barred, work out the total cost of each year with its surcharge, assess the exposure in case any figure comes close to the criminal threshold, and propose a filing order with exact dates. Then we file everything and see through whatever comes afterwards, including a deferral if needed. If this is your situation, tell us through the late filing form, or first see how we handle it. We warn you of every risk we see, and we do not promise that a file will be closed without a review: that does not depend on us.