How to register as a self-employed worker in 2026: steps, documentation, and mistakes that cost money

The criterion of habituality over the volume of income

This obligation applies both to professionals dedicated exclusively to their business and to employees in a multi-activity regime, to Economically Dependent Self-Employed Workers (TRADE), and to those who receive reduced but continuous income over time.

Strategic decisions prior to the official procedure

• Application for unemployment benefit capitalization: Those receiving unemployment benefits and wishing to apply for a one-time payment to invest in the business or cover fees must complete the procedure before registering any official registration. Formalizing the registration first invalidates the right to receive this money definitively.

• Selection of the IAE heading and CNAE code: They classify the economic activity and impose the applicable regime in the IRPF and VAT, as well as the tax models to be submitted. Choosing an incorrect heading requires subsequent correction within a month.

The mandatory procedure in two phases

1. Registration with the Tax Agency (Model 036): Following the definitive elimination of Model 037, Model 036 is the only valid route for individuals. It is submitted electronically and free of charge at the Electronic Headquarters of the Treasury using a digital certificate, DNIe, or Cl@ve. It declares the tax domicile, the IAE heading, the IRPF modality (usually Simplified Direct Estimation), and the VAT regime.

2. Registration in the RETA (Import@ss): It is processed on the digital platform of the General Treasury of the Social Security. During the process, the contribution base must be selected according to the expected net income, a collaborating mutual must be designated, and the reduced rate box must be explicitly checked. Omitting this check prevents the request for the discounted fee later on.

The six irreversible mistakes that generate extra costs

1. Reversing the official order: Registering with Social Security before the Tax Agency breaks the legal procedure.

2. Invoicing before the registration date: The date of the first income or issued invoice determines the actual start of the activity before the law.

3. Forgetting to request the reduced rate: The system does not accept requests for bonuses after completing the registration form in Import@ss.

4. Processing the registration before the one-time unemployment payment: Automatically invalidates the collection of accumulated unemployment benefits.

5. Not selecting a collaborating mutual: Causes the Treasury to assign an entity by default without the user's criteria.

6. Not knowing the maintenance of the fee: The obligation of monthly payment to Social Security remains even if the invoicing is zero, which requires processing the official cancellation if the activity stops.