Pre-incorporation prep

Decide your company name (3 alternatives in order of preference)You submit all three to the Registro Mercantil Central; they grant the first available.
Request certificación negativa de denominaciónConfirms the name is available. Apply at the Registro Mercantil Central (online via sede.registradores.org). Costs ~€16, valid 3 months. Takes 3-5 days.
Define share capital (€1 minimum since 2022 reform)Most SLs still use €3,000 for credibility. If you choose < €3,000, the company is subject to special "Sociedad Limitada en Régimen de Formación Sucesiva" rules.
Draft articles of incorporation (estatutos sociales)Define the company purpose, governance, share structure. A gestor or business lawyer typically prepares these.
Identify partners and their share allocationsSole-shareholder SLs (Sociedad Limitada Unipersonal — SLU) are allowed and common for solo founders.

Provisional NIF + bank account

Obtain provisional NIF for the companyFile Modelo 036 at Agencia Tributaria with the certificación negativa. Lets you operate before the definitive registry.
Open a corporate bank accountWith the provisional NIF + certificación negativa. Sabadell, BBVA, CaixaBank handle SL formations regularly.
Deposit the share capitalBank issues a certificate (certificado bancario) confirming the deposit. Required at the notary.

Book an appointment with a notaryAny notary in Spain can incorporate an SL. Online comparison sites (notariado.org) help.
Bring all incorporators with valid IDEach partner / authorised representative must sign in person (or via apostilled power of attorney).
Sign the escritura de constituciónNotary reads the deed, partners sign. Notary fees: €300-€600.
Receive copia autorizada and copia simpleYou need the copia autorizada for the Registro Mercantil filing.

File at your provincial Registro MercantilSubmit the escritura within 2 months of signing. Registry fees: ~€150. Processing 2-4 weeks. You receive the company's definitive registration.
Update Modelo 036 with the definitive NIFReplace the provisional NIF with the definitive one assigned by the registry.
Pay Impuesto sobre Transmisiones (typically exempt for SL formation)SL formations are exempt from the 1% capital tax under current law, but you must declare and confirm exemption.

Register company at Social Security (Código de Cuenta de Cotización — CCC)Required before hiring any employees. Even sole-administrator SLs need a CCC.
Register the administrator with RETADirector-administrators must register as autónomo (RETA) in addition to the company.
Hire a gestor or asesor fiscalSL accounting and corporate filings are complex. Monthly retainers €60-€200 are standard and worth it.
Set up online banking and accounting softwareHolded, Anfix, Quaderno are popular SL-friendly tools.
File Modelo 200 (annual corporate tax) once per yearDue 25 July for calendar-year accounting periods. 25% standard rate; 15% for first 4 years for new companies.

Apply to ENISA for empresa emergente certification (optional)Unlocks 15% corporate tax for first 4 years, tax-free stock options up to €50k/year, simplified online incorporation.
Verify eligibility (optional)Company < 5 years old (7 for biotech), has not distributed dividends, meets innovation criteria.