Standard KYC requires a valid passport or EU national ID (a standalone NIE slip is a number registry, not an identity document, and must be paired with a passport); an active NIE is mandatory for all accounts, updated to reflect the physical green A4 sheet or TIE card for residents. Proof of address: a fresh Volante de Empadronamiento (issued within 3 months) or a matching utility bill for residents; a recent bank statement or foreign tax certificate for non-residents. Under Spain's AML law (Ley 10/2010), source-of-funds verification requires an active employment contract, a recent tax declaration, or three consecutive payslips; self-employed applicants supply the Vida Laboral report plus quarterly VAT returns (Modelo 130/303). In-branch accounts can activate within 1-2 hours; digital onboarding (via Spanish Citizen Card or Firma Digital, with facial biometrics) takes 24-48 hours.