Registering as an autónomo
There are two separate registrations: the business census at the Tax Agency and RETA at Social Security. Both have to cover the day you start working.
Census and Social Security
The census registration is filed before the activity starts. The Tax Agency treats the activity as started when you deliver goods, provide services, buy, collect, pay, or hire staff for that activity. RETA is a different filing, at Social Security, and it does not replace the census.
- Census: modelo 036 or, if your case fits, modelo 037.
- RETA: Social Security, from the start date.
- Only one of the two does not complete the registration.
The app does not register you
Factura Fácil does not file modelo 036 and does not enrol you in RETA. Once you have the PDF of the registration, the DUE, or modelo 036, you can upload it to fill in your profile. If the file is not read, it is kept and you complete the data yourself. Issuing an invoice in the app does not tell the Tax Agency you have registered.
Common questions
Can I invoice on the day I register?
The invoice date has to fall on a day when you are already on the census and in RETA. The census filing comes before you start.
Does Factura Fácil file modelo 036?
No. Modelo 036 or 037 is filed on the Tax Agency site. The app can only store the PDF once you already have it.
Official sources
Informational text reviewed on 26 September 2026. It is not tax advice and does not replace the Spanish Tax Agency or your accountant. Deadlines, rates, and forms can change.