Registering for Spanish business tax: who files, and on which form

The short answer

Hardly anyone registers in the register of the Spanish tax on economic activities, because hardly anyone pays that tax. And those who do register do not always use form 840: if their town hall has delegated census administration, the form is a different one and so is the counter.

Two registers that get confused all the time

When somebody starts a business they file a census declaration, form 036 or 037, and state their IAE heading on it. That makes it look as though they have already registered for the tax, and they have not. Registration in the register of the IAE is a separate return, and the first paragraph of article 5.1 of Royal Decree 243/1995 says who it reaches: «taxpayers who are not exempt from the tax».¹

The difference is enormous in practice, because the exemption in article 82.1.c) of the consolidated Act covers every individual without exception and companies with net turnover «below 1,000,000 euros».⁴ That threshold is exclusive, and it is worth reading slowly: at exactly one million the exemption is gone, because «below» does not include the figure itself.

The second paragraph of the same provision adds the taxpayer nobody expects: anyone who had been applying an exemption «when they cease to meet the conditions required for it».¹ That is the company that grows and crosses the million.

Who files nothing, and the exception identified by heading number

There is a third relief almost no guide mentions. The third paragraph of article 5.1 leaves out anyone carrying on activities «whose resulting quota is zero, whether because that follows from the tariffs or because the State administration has so declared». And then it adds an exception identified by number: «with the exception of economic interest groupings and temporary business consortia classified under heading 508 of section 1 of the tariffs», which must file a registration return under paragraph 3 of rule 15 of the Instruction.¹

A relief with an exception named by heading number is the kind of detail that decides whether a consortium has paperwork at all, and it appears in no summary.

The form depends on your municipality

This is what this page exists to say. Article 8 of the regulation has two paragraphs. The first allocates the offices when census administration is the State's. The second says something else:

Where census administration is carried out by delegation, registration, variation or deregistration returns shall be filed at the offices of the relevant body, in the manner and on the forms it determines.¹

It is not form 840 handed in at a different desk: it is whichever form that body decides. Where that delegation comes from is explained by article 91.1 of the consolidated Act, and its limit is the useful part. Forming the register, classifying activities and «census administration of the tax in general» belong to the State, but «in the case of municipal quotas» those functions «may be delegated to town halls, provincial councils, island councils and other bodies recognised by law and by the autonomous communities that request it».⁴

In other words: delegation exists only for the municipal quota. If you are taxed by provincial or national quota, census administration is the State's whatever happens and the form is the 840 with no further questions. Which municipalities have delegated it is published by no citable national register, so it is something to ask at the town hall or provincial council itself.

One activity is one return, and a warehouse is another

Article 5.2 requires returns to be made «separately for each activity».¹ And it adds the rule that multiplies the paperwork of anyone with a warehouse: with a municipal quota and premises in which the activity is not directly carried on, those in letter h) of section F of rule 14, «a return shall be filed for each of those premises, although for the purposes of the subsequent assessment only the surface area element shall be taken into account».

With a provincial or national quota the rule inverts: the following paragraph requires the return to list «all premises, whatever their location and use, adding together the surface area of all of them».¹ The same three warehouses that add three returns on a municipal quota add none on a provincial one.

The annex that carries them has its own name: paragraph One of Order HAC/2572/2003 approves, «as an annex to form 840», the «list of premises», and specifies that the form's reference number is «a sequential number whose first three digits shall correspond to code 890».²

Four possible offices, and one change filed at two

Article 8.1 allocates filing by quota class: with a municipal quota, to the office «whose territorial area corresponds to the place where the activity is carried on», except the return for indirect premises, which goes «to the place where the premises are located»; with a provincial quota, to the provincial office of the territory where the activities are carried on; with a national quota, to the one for the tax domicile.¹

And letter d) adds the case nobody expects. Variations caused by a change of quota class «must be filed at the offices where the returns being amended were filed and also, where applicable, at the offices corresponding» to the new class.¹ Two filings for one change. Article 6.1 also recalls that such a change is a variation whose effects begin in the following tax period, unless deregistration and registration returns are filed instead.

You file it with one administration and a different one decides

Article 9.1 requires reliefs and tax benefits granted on application to be requested «when filing the registration return in the tax register».¹ It is not a separate step to be taken later: it goes in the registration return or it is lost for that period.

And the body that decides is not the body that receives. Article 9.2 says that with a municipal quota and State census administration «the body receiving a registration return in which recognition of a tax benefit is requested shall forward it to the competent town hall, so that the latter adopts the relevant decision and notifies the interested party».¹ Article 91.2 of the consolidated Act confirms it: assessment, collection and «the functions of granting and refusing exemptions and reliefs» belong to the town hall.⁴

You file with the tax office, your town hall answers you and your town hall bills you. And if you want to challenge the census act, article 91.4 sends you to the State Economic-Administrative Tribunals, even when the act was issued by a town hall under delegation.⁴

A year after the deadline the electronic channel ends

Paragraph Four.Three of Order HAC/2572/2003 is blunt:

Electronic filing of form 840 returns may not be carried out once more than one year has elapsed since the end of the deadlines set out in paragraph six of this Order. Once those periods have passed, the return must be filed using the corresponding paper form.²

That is the opposite of what has happened with the other forms in the system, where paper was progressively suppressed. And it survives for a reason you can check in a single reading: Order HAP/2194/2013, the one that suppressed paper for information returns, enumerates in its article 1 the forms it applies to (one hundred and twenty-nine of them, across three lists: sixty self-assessments, fifty-eight information returns and eleven census filings), and neither the 840 nor the 848 appears in any of the three. Not even in the census list, which is precisely the family they belong to, and so the one a sceptical reader would check. And it is an article with forty-six versions, the latest in force since 1 January 2026, i.e. actively maintained.⁵ It cannot have repealed a channel of a form that falls outside its scope. It is also why the 2003 text still speaks of X.509 certificates from the Royal Mint: nothing has reached in to modernise it.

Form 848, and the only date in the pair

The third paragraph of article 90.2 of the consolidated Act requires non-exempt taxpayers to report their net turnover to the tax office, and also its variations when these change the exemption or «the band to be considered for the purposes of applying the weighting coefficient provided for in article 86».⁴ The form is the 848, and paragraph One of Order HAC/85/2003 empties that duty almost entirely: exempt taxpayers are relieved of it and so are non-exempt ones who have already stated that figure in the last corporation tax return filed before 1 January of the year it takes effect, or in the information return provided for civil-law partnerships and entities without legal personality.³

In a group of companies under article 42 of the Commercial Code the relief is conditional on the parent having stated the group's combined figure, so having your own properly declared is not enough.³

And the date is the oddest thing about the two forms. Paragraph Six of the form 840 Order sets none: it refers back «to the deadlines regulated in articles 5, 6 and 7».² The 848's, by contrast, sets its own, and it is not a bare deadline but a window with both ends written down: its paragraph Three requires the communication to be filed «within the period running from 1 January to 14 February, both inclusive, of the year in which it is to take effect».³

The opening day matters as much as the closing one, and it is the half almost nobody counts: the communication cannot be filed before 1 January of the year in which the figure takes effect. And if 14 February falls on a Saturday, a Sunday or a national holiday, the deadline moves to the next working day under article 30.5 of Act 39/2015. In 2026 the 14th is a Saturday, so the last day is Monday 16 February.

The preamble to that same Order puts it differently, «before 15 February», and it agrees in effect, because «before the 15th» and «up to and including the 14th» end on the same day. But paragraph Three is the operative provision, and it is the only one of the two that writes down the day the window opens.

A worked example with real numbers

A company with 2,000,000 euros of net turnover asks about its IAE for 2026. It is not exempt, so it must appear in the register.

If it is taxed by municipal quota in a municipality whose census administration is the State's, its form is the 840 and it files at the tax office for the place where it operates. If that same municipality has delegated census administration, its form stops being the 840 and becomes whichever one the delegated body decides, at that body's counter. And if it were taxed by provincial or national quota, the answer would be form 840 in both cases, because delegation does not reach there.

With two activities and three warehouses nobody works in, a municipal quota means five returns at two different offices: the one for where it operates and the one for where the warehouses are. A provincial quota means two returns, because the three warehouses are listed in them and their surface areas added together.

And since its turnover appears in its corporation tax return, it does not file form 848. If it appeared in no return, it would have until Monday 16 February 2026 to file it.

What this page does not calculate

The deadline for each return and the amount of the tax. Both are resolved by our IAE calculator, which says whether you are exempt, which year you start paying, in which month the registration return is filed and what the quota comes to with the local multipliers. And the heading, which is the code everything else follows from, is in what an IAE heading is.