Apply for the Beckham Law special regime (Modelo 149) — a flat 24% tax on Spanish-source income up to €600,000 for up to six years, for qualifying inbound workers (employees and, since 2023, many remote workers and entrepreneurs; usually not standard autónomos). The election has a strict filing window (~6 months from starting your activity) — confirm eligibility and timing with a tax adviser

The special inbound-workers regime the title describes: qualifying newcomers can elect a flat rate on Spanish-source income for a limited period, instead of standard progressive rates. The title carries its own warning — the election window is strict and eligibility has sharp edges (standard autónomos usually don't qualify) — so treat this as a decision to make with a tax adviser the moment your activity starts, not at your first renta.