Posted Workers, A1 Certificates, and EORI Numbers for Companies in Spain

Posting workers to Spain: the EU framework

An EU posted worker is someone their employer sends temporarily from one member state to work in another, Spain in this case, while staying employed by, and socially insured through, the sending company back home. Posting is genuinely different from opening a Spanish payroll for that person: the worker does not become a Spanish employee, Spanish Social Security is not the system paying their contributions, and no Spanish work visa is involved, because EU and EEA nationals move freely under EU freedom-of-movement rules regardless of where within the bloc they are actually working.

What makes a posting genuine, rather than a Spanish role dressed up as a posting, is substance: the assignment has to be time-limited with a real return plan, and the posting company has to keep actually directing the work, not hand over day-to-day control to the Spanish counterpart as if that company were the real employer. Getting this distinction right matters because a posting that drifts into looking like ordinary Spanish employment, without being registered as one, creates exposure that resembles the illegal labour-supply risk we cover in detail on our EOR vs entity Spain guide. The same substance question comes up when a foreign company is deciding between a Spanish subsidiary or a branch to house posted staff long-term.

A1 certificates: avoiding double Social Security

The A1 certificate is the document that makes a posting work administratively. Issued by the worker’s home-country social security authority, it confirms they remain covered by that system while working temporarily in Spain, so Spanish Social Security contributions are not also owed on the same earnings. Without a valid A1 on file, a posted worker risks exactly that double exposure, and the Spanish authorities treating the assignment as ordinary local employment rather than a genuine posting, with the registration and contribution gap that implies.

Getting the A1 in place before the assignment starts, not retroactively once someone asks for it, is the single most common piece of advice worth repeating here. It is a home-country filing, so the lead time depends on the sending country’s own social security administration, which is exactly the kind of dependency that catches companies planning a posting on short notice.

Desplazamiento notifications: the Spanish-side filing

Alongside the A1 certificate sits a separate obligation: the desplazamiento notification, the formal declaration a foreign company must file with the Spanish labour authorities before posting a worker here. This is not a substitute for the A1, and it is not optional paperwork that only matters for large postings; it applies to the posting itself, regardless of how brief the assignment is meant to be. The posting employer, not the Spanish company receiving the worker, is responsible for filing it.

We treat the A1 certificate and the desplazamiento notification as a single coordinated filing exercise rather than two separate errands, because in practice they need to land in the same window before the worker’s start date, and a company juggling both for the first time is the company most likely to file one and forget the other.

EORI numbers and customs basics for companies trading through Spain

An EORI (Economic Operators Registration and Identification) number is the customs identifier every company needs to import, export, or otherwise move goods through EU customs, including trading through Spain specifically. Without a valid EORI attached to the shipment, customs clearance simply stalls, which is the single most common reason we see a company’s first shipment sitting at the border longer than expected.

A company applies for its Spanish EORI through the Agencia Tributaria, using its Spanish tax identification (NIF), and once issued the number is valid for customs purposes across the whole EU, not only for Spanish shipments. Foreign companies without an existing Spanish NIF typically need that registration in place first, which is why we sequence EORI applications alongside company formation and tax registration rather than treating it as an afterthought once goods are already ready to ship.

Intrastat: the reporting obligation that catches active traders off guard

Intrastat is the EU’s statistical reporting system for the physical movement of goods between member states, and it is a separate obligation from both VAT returns and customs declarations. It becomes a live filing requirement once your arrivals or dispatches cross the threshold Spain’s tax authority sets, and that threshold is reviewed periodically rather than fixed indefinitely. Company size on its own is not an exemption: a smaller but genuinely active trading company can cross the threshold without expecting to, simply because Intrastat measures actual goods movement rather than headcount or revenue.

We check your real trade volumes against the current threshold directly rather than assuming either way, since assuming you are too small is exactly the assumption that leads to a missed filing once trade actually picks up.

Common compliance traps, and how they connect to staff you cannot post

The recurring pattern across posted-worker and customs compliance is timing, not complexity: A1 certificates requested after the posting has already started, desplazamiento notifications filed late because the A1 process ate the available lead time, EORI applications left until a shipment is already stuck at the border, and Intrastat obligations that go unnoticed because nobody checked the threshold. Each of these is genuinely avoidable with a short lead-time check before the assignment or shipment happens, and genuinely expensive to unwind after.

One structural trap sits underneath all of this: posted-worker rules under the A1 and desplazamiento framework only cover EU and EEA nationals moving under freedom of movement. Non-EU staff you want to bring to work in Spain need a sponsored immigration route instead, most commonly our work visa Spain or highly qualified visa Spain process, run alongside the company’s own payroll and customs compliance rather than as a substitute for it. Companies that assume “posting” covers any relocated employee, EU or not, are the ones who discover the gap only once a non-EU hire is already meant to be on-site.

Payroll registration, VAT, and the recurring compliance calendar that sits behind both are covered in full on our payroll and VAT for foreign companies guide, and this page’s obligations frequently run in parallel with that one for companies that both employ and trade in Spain at the same time.