Conversion IAE CNAE: The Definitive Business Guide for Spain

If you plan to start a business, register as a freelancer, or restructure your company in Spain, one crucial step is often overlooked: the correct classification of your activity.
Spain uses two official systems to define and categorize economic activities — the IAE (Impuesto sobre Actividades Económicas) and the CNAE (Clasificación Nacional de Actividades Económicas).

At first glance, these systems may seem similar, but they serve different legal and administrative purposes. The process known as conversion IAE CNAE bridges the gap between them — ensuring that your fiscal (tax) and administrative (statistical) records align perfectly.

This guide will walk you through everything you need to know: what IAE and CNAE mean, why the conversion matters, how to perform it correctly, and how to avoid costly registration errors.

1. What Is IAE and Why Is It Important?

The IAE, or Impuesto sobre Actividades Económicas, is Spain’s official tax classification system for all business and professional activities.
It’s regulated by the Agencia Tributaria (AEAT) and determines how your business is taxed, which deductions apply, and what fiscal obligations you have.

Each activity has a specific IAE epígrafe (code), categorized under three main sections:

• Section 1 – Business Activities: Industry, trade, manufacturing, and commerce.

• Section 2 – Professional Activities: Consultancy, marketing, design, law, IT, healthcare, etc.

• Section 3 – Artistic Activities: Performing arts, creative work, entertainment, and similar sectors.

Examples of IAE codes:

• IAE 843.9 – Advertising and marketing services.

• IAE 861.1 – Legal consultancy.

• IAE 661.2 – Retail sale of clothing.

The IAE code you select determines your tax treatment and must appear in your Modelo 036 or 037 when registering with the AEAT.

2. What Is CNAE and What Role Does It Play?

The CNAE (Clasificación Nacional de Actividades Económicas) is managed by the Instituto Nacional de Estadística (INE).
Unlike the IAE, which serves tax purposes, the CNAE is used for statistical and administrative classification of economic activities.

It helps government agencies collect data, monitor economic trends, and coordinate with European Union standards (via the NACE system).

Examples of CNAE codes:

• CNAE 7311 – Advertising agencies.

• CNAE 6910 – Legal activities.

• CNAE 4719 – Retail trade in non-specialized stores.

You’ll need your CNAE when:

• Registering a company or self-employment activity.

• Applying for Social Security or employment insurance.

• Requesting government funding or grants.

• Filing economic or sectoral statistics.

In essence:
🧾 IAE = Tax identification
📊 CNAE = Economic classification

3. Why the Conversion IAE CNAE Matters

Even though both codes describe your activity, they are used by different authorities for different purposes.
The conversion IAE CNAE ensures your fiscal records (AEAT) and administrative data (INE, Social Security, or town councils) describe the same activity.

Failing to convert correctly can cause:

• Rejection of grant or subsidy applications.

• Licensing delays or denials.

• Data inconsistencies between AEAT, INE, and municipal offices.

• Risk of compliance penalties during audits.

For example, if your IAE code defines your work as “marketing” but your CNAE says “software development,” authorities may flag your application as inconsistent.

4. Key Differences Between IAE and CNAE

Because these systems evolve separately, one IAE code can correspond to multiple CNAE codes, or vice versa.
Hence, performing the correct conversion using verified data sources is vital.

5. Step-by-Step Guide: How to Perform Conversion IAE CNAE

Follow this process to ensure your activity is classified correctly:

Step 1: Define your main activity

Write a short, precise description of what your business does.
Example: “Online advertising and brand consultancy.”

Step 2: Identify your IAE code

Use the official list from the Agencia Tributaria or tools like ConversorIAECNAE.es.
Example: IAE 844 – Advertising and marketing services.

Step 3: Find equivalent CNAE codes

Enter your IAE into a trusted converter or check equivalence tables from SuperContable.com.
Example: IAE 844 corresponds to CNAE 7311 (Advertising agencies) and CNAE 7021 (Public relations consultancy).

Step 4: Choose the most accurate CNAE

Select the code that best describes your primary business.
For a marketing agency, CNAE 7311 would be ideal.

Step 5: Apply both codes consistently

Include both IAE and CNAE in all official documents — business registration, tax forms, licenses, and grant applications.

6. Example of Real Conversion IAE CNAE

Let’s imagine you operate a web design and branding studio in Madrid:

• IAE code: 843.1 – Graphic design and visual communication.

• Possible CNAE codes:

  • 7410 – Specialized design activities.

  • 6201 – Computer programming services.

Since your focus is design rather than programming, the correct equivalence for conversion IAE CNAE is CNAE 7410.

This ensures that both your fiscal and administrative profiles match across AEAT and INE databases.

7. When to Update Your Conversion IAE CNAE

You should review or update your codes when:

• Expanding your services or adding new activities.

• Changing your business model (e.g., from retail to e-commerce).

• Updating your company’s legal structure.

• Applying for new funding programs that require specific CNAE identification.

• New CNAE versions are published (such as CNAE 2025).

Staying current ensures accuracy across all agencies and prevents classification mismatches.

8. Best Tools for Conversion IAE CNAE

Save time and avoid mistakes by using reliable online tools and official sources:

• ConversorIAECNAE.es – Interactive and updated equivalence database.

• SuperContable.com – Offers equivalence charts and fiscal advice.

• Cámara de Comercio de Sevilla – Official business advisory services.

Cross-check results with the AEAT and INE websites before completing registrations.

9. Common Mistakes in Conversion IAE CNAE

Avoid these common pitfalls:

1. Using outdated or unofficial conversion tables.

2. Selecting a code by its number instead of its description.

3. Copying codes from another business without reviewing your actual activity.

4. Forgetting to update after a change in services or structure.

5. Registering the wrong CNAE, which may disqualify you from certain sectoral grants.

Accuracy protects your business credibility and ensures seamless relations with Spanish authorities.

10. Pro Tips for Maintaining Compliance

✅ Always confirm you’re using the latest CNAE version (CNAE 2025).
✅ Save your conversion proof for tax audits.
✅ For multi-service businesses, register secondary CNAE codes.
✅ Consult a gestoría fiscal (tax advisor) if you operate in multiple industries.
✅ Keep your IAE and CNAE consistent across all official filings.

11. Final Thoughts: Why Conversion IAE CNAE Matters

The conversion IAE CNAE may look like a minor technicality, but it plays a major role in Spain’s business ecosystem.
It connects your fiscal classification (IAE) with your administrative identity (CNAE), ensuring that every public institution — from the Tax Agency to the National Statistics Institute — recognizes your business the same way.

Getting this conversion right means:

• Smoother business registration.

• Access to funding and subsidies.

• Compliance with tax and labor authorities.

• Credibility when dealing with partners, banks, and clients.

In short, mastering the conversion IAE CNAE process gives you control, compliance, and confidence. It’s a small but vital step toward building a professional, transparent, and future-proof business in Spain.