Yes. I'm autonomo and have been for the last 11years.

You will pay (currently) 275 euros a month in social security payments and if you pay in for enough years you get a pension - you pay this irrespective of whether you earn any money or not. You aren't eligible for any unemployment benefit or sickness benefits of any form.  I believe there is a scheme at the moment where you pay less for the first few months - a gestor would be able to advise.

You should go to a gestor and they will register you with the tax office as autonomo. You will then be required to file quarterly accounts and vat (IVA) returns.

I use a gestor for everything as it's much easier that way and they are up to date with current legislation/rules etc.

Nigel