Before you start

Proof you can be in Spain legally for >3 months: an EU passport (EU route) OR an approved visa/residence authorisation such as the Digital Nomad Visa (non-EU route)
A Barcelona address you can document — a lease in your name, or a landlord's authorisation letter plus a copy of their ID
Passport valid well beyond your intended stay; private health insurance if your route requires it

Step-by-step

1
Get your empadronament at the Ajuntament (do this first)
Register on Barcelona's padró municipal d'habitants at an Oficina d'Atenció Ciutadana (OAC). Book a cita previa at ajuntament.barcelona.cat or by calling 010. You walk out with the volant d'empadronament the same day. You can usually register before you have an NIE — the padró is address-based — and it's what later unlocks your CatSalut public-health card.
In personWho: You (each adult registers individually)Same-day certificate once you have the appointment; slots release in batches ~2-3 weeks outFree
2
EU/EEA/Swiss: apply for the green certificate (certificado de registro + NIE)
If you'll stay over 3 months you must register as an EU national at the Oficina d'Estrangeria / Policía Nacional in Barcelona province. Book cita previa under 'CERTIFICADO DE REGISTRO DE CIUDADANO DE LA UE', bring form EX-18 and the paid 790-012 fee, plus proof you're working, self-employed, or self-sufficient with health cover. They hand you the green A4 paper carrying your NIE on the spot. (Non-EU citizens skip to the visa step.)
In personWho: EU/EEA/Swiss citizensIssued at the appointment; the bottleneck is getting the cita~€12 (modelo 790-012; verify current amount)
3
Non-EU: secure your visa or residence authorisation
Pick a route before arrival. The Digital Nomad Visa (2023 Startups Law) suits remote workers paid by non-Spanish companies; apply at a Spanish consulate for a 1-year visa, or from inside Spain to the UGE-CE for a 3-year authorisation. You'll need proof of income (~200% of the SMI), a degree or 3+ years' experience, a clean criminal-record certificate, and health insurance.
OnlineWho: Non-EU professionals (consulate or UGE-CE; employer may sponsor work permits)Consulate decision target ~10 working days; in-country UGE-CE ~20 working daysVisa/permit fees vary by route and consulate
4
Non-EU: book 'toma de huellas' and collect your TIE in Barcelona
Once your authorisation is approved you have 30 calendar days to give fingerprints. Book cita previa under 'POLICÍA - TOMA DE HUELLAS' for Barcelona province, bring your EX-17, the paid 790-012 fee, a photo and your empadronament. The physical TIE card is ready in roughly 30-45 days — and in Barcelona province you can now usually just turn up to collect it.
In personWho: Non-EU residentsFingerprints within 30 days of approval; card ready ~30-45 days later~€16-21 TIE issuance (modelo 790-012; hedge)
5
Register your address with CatSalut for public healthcare
With your empadronament and NIE/TIE, register at your local CAP (Centre d'Atenció Primària) to get the TSI (Targeta Sanitària Individual), Catalonia's public-health card. This is run by the Generalitat de Catalunya, not the national system — a distinctly Catalan step, and why the padró matters so much.
In personWho: You, at your assigned CAPCard follows by post after registrationFree at point of access

Documents you’ll need

Passport (EU national ID for EU citizens), valid well beyond your stay
Form EX-18 (EU green certificate) or EX-17 (non-EU TIE), completed in Spanish
Paid fee receipt — modelo 790, code 012
Proof of Barcelona address for the padró: lease in your name, or landlord authorisation + copy of their ID

Things most newcomers don’t know

The empadronament is the hidden master key — sort it first.

In Barcelona the padró gates your CatSalut TSI health card, school places, the TIE, and most paperwork. Because it's address-based you can often register before your NIE, so it's the one thing to lock down in week one.

Source: Ajuntament de Barcelona (padró)

Cita previa scarcity is the real adversary, not the rules.

Barcelona's Oficina d'Estrangeria NIE/TIE appointments are notoriously hard to land and get resold by 'gestores'; the padró cita is easier but still drips out in batches. The substance of each step is quick — the wait is purely getting the slot.

Source: expat-guide + community consensus

NIE is the number; TIE/green certificate is the document.

Non-EU residents carry a physical TIE card (your NIE printed on it); EU citizens get the green A4 paper with the same NIE. People conflate them, book the wrong cita, and lose weeks.

Source: Policía Nacional / Oficina de Extranjería

Same federal law as Madrid, but everything is Catalan and local.

Forms can come in Catalan, the city office is the Ajuntament de Barcelona, the foreigners' office is Barcelona's, and healthcare runs through the Generalitat's CatSalut — so generic 'Spain' instructions miss where you actually go.

Source: Generalitat de Catalunya / Ajuntament

Common mistakes to avoid

Skipping the padró: without the volant d'empadronament you can stall your TIE appointment and can't get the CatSalut TSI health card at your CAP.
Missing the 30-day fingerprint window: once your non-EU permit is approved the clock starts immediately.
Booking the wrong cita previa: choosing the EU 'certificado de registro' option as a non-EU applicant (or vice-versa) wastes a scarce appointment slot.
Trusting a single DNV income figure: sources cite ~€2,762 to ~€2,850/month depending on how the 14-payment salary is annualised — confirm with the consulate or UGE-CE.