CNAE and IAE in Spain: Two Different Codes That Most Foreign Founders Confuse
When setting up a Spanish company, you will encounter two activity classification codes: the CNAE and the IAE. They look similar, they describe the same business activity, and they are used by entirely different systems for entirely different purposes. Choosing the wrong one — or conflating the two — creates downstream problems with tax registration, banking and Social Security.

Two Systems, One Activity

Every Spanish company must declare what it does. The problem is that two separate classification systems require this declaration — and they are administered by different public bodies, use different code structures and serve different functions.
The CNAE (Clasificación Nacional de Actividades Económicas) is Spain's national standard for classifying economic activities. It is a four-digit statistical code maintained by the INE — the National Statistics Institute — and is the Spanish implementation of the EU's NACE classification system. The CNAE is used by Social Security to determine contribution rates, by the INE for economic statistics, and by the Agencia Tributaria when filing corporate income tax returns and certain VAT declarations.
The IAE (Impuesto sobre Actividades Económicas) is a tax — specifically, a municipal business activity tax — and its classification system, the IAE epígrafe, is used by the Agencia Tributaria to identify what economic activity a company or professional is authorised to conduct for tax purposes. The IAE epígrafe determines whether VAT applies to your activity and at what rate, which reporting obligations arise and how the Agencia Tributaria categorises your company in the tax census.

What Each Code Actually Controls

Understanding what each classification controls in practice makes the distinction concrete.
The CNAE code appears in the company's Articles of Association, in the Modelo 036 census declaration, in the corporate income tax return (Modelo 200) and in Social Security filings. For most operational purposes, the CNAE is a statistical identifier — it tells the administration what sector your business belongs to, but does not directly determine your tax liability. However, the CNAE you declare on the corporate tax return must correspond to your actual primary activity, and inconsistencies between the CNAE on the Escritura and the CNAE on tax filings generate reconciliation flags.
The IAE epígrafe controls how your company is classified for tax activity purposes. It determines whether your services are subject to VAT, whether you qualify for certain VAT exemptions, and which tax obligations you must fulfil. A technology consulting firm registered under a manufacturing IAE epígrafe will have a mismatched tax profile. A professional services company that selects a retail trade epígrafe will face questions about its invoicing and VAT treatment.
For most companies with annual turnover below €1 million, the IAE itself is not a tax they pay — there is an exemption at that threshold. But the IAE classification system is still used to categorise the activity, and choosing the wrong epígrafe affects everything built on top of it.

CNAE-2025: The Classification Was Updated

A further complexity for companies incorporated from 2025 onwards: Spain updated the CNAE classification system itself. CNAE-2025 entered into effect in January 2025, introducing revised codes and reorganized activity categories that partially diverge from the previous CNAE-2009 system.

Companies incorporated before 2025 retain their CNAE-2009 codes. Companies incorporated from 2025 onwards should use the CNAE-2025 classification. During the transition period, both systems remain in use across different government platforms — creating a situation where the CNAE on the Escritura may use one classification version and the code required on a specific tax form may reference another.

For foreign founders working with a gestoría or legal advisor on their Spanish SL, confirming which CNAE version is being applied — and ensuring it is consistent across all documents — is a specific point worth verifying.
Why the Confusion Causes Banking Problems
Spanish banks reviewing corporate account applications assess the consistency between the company's declared activity across all documents. The compliance team compares the CNAE in the Articles of Association against the IAE epígrafe on the Modelo 036, against the business model description in the banking application, against the expected transaction profile.

When a company's CNAE code describes one type of activity and the IAE epígrafe describes another — both of which are plausible but do not correspond precisely to what the founder actually does — the compliance officer sees inconsistency. This is not a deliberate misrepresentation, but it reads as one.
The most common version of this problem occurs with digital businesses, consulting companies and technology firms, where the boundaries between CNAE and IAE categories are genuinely ambiguous and advisors sometimes make expedient choices rather than precise ones. A founder who describes their company as a "technology consultancy" to their advisor may end up with a CNAE for software development and an IAE epígrafe for general management consulting — plausible individually, but misaligned with each other and with what the bank expects to see.
What to Do If Your Bank Account Was Refused

How to Approach the Code Selection Correctly

The Registro de Operadores Intracomunitarios (ROI) is the EU VAT identification register. A Spanish company that buys from or sells to VAT-registered businesses in other EU member states must be registered in the ROI before conducting the first intra-EU transaction.

Registration is completed by ticking box 582 on Modelo 036. It assigns the company a VAT number with the ES prefix that is recognised across the EU and listed in the VIES database — the cross-border VAT verification system used by companies throughout the single market.

Many foreign founders setting up Spanish SLs skip the ROI registration at the initial filing stage, either because their advisor does not raise it or because they do not anticipate immediate EU-side business. The problem arises when the first EU client requests the company's VAT number for their invoice — at which point the company must file a Modelo 036 modification, wait for ROI registration and delay invoicing.

For a Spanish SL intended as an EU operational vehicle — which is the case for most international founders — ROI registration should be included in the initial Modelo 036 filing, not added later.
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Continue Reading — Company Formation in Spain

→ Modelo 036 in Spain: What It Is and How to File It Correctly 
→ ROI Registration in Spain: The Intra-EU VAT Number Most Companies Miss 
→ Provisional NIF vs Permanent NIF in Spain

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