Register as self-employed: file Modelo 036 with Hacienda, then register with Social Security (RETA) the same day or within 60 days (Modelo 037 was abolished in 2025)

Becoming self-employed in Spain is a same-week double registration, exactly as the title lays out: the tax census filing with Hacienda (Modelo 036), then Social Security's self-employed scheme (RETA) inside the title's window. Order matters, and the timing rules changed recently (the title notes the old form's abolition) — a gestor makes this a single errand.