A1 Certificate Portugal: Guide to Posting Workers Abroad and Social Security Rules

INLIS Consulting
2 hours ago
6 min read

How the A1 Certificate keeps Portuguese workers covered by Portugal’s social security when posted abroad. Step-by-step employer and freelancer guide, durations, documents, and country rules.

A1 Certificate Portugal — Complete Guide for Posting Workers Abroad

If you’re an employer sending staff abroad, or a self-employed person planning temporary work outside Portugal, you need to know which social security rules apply, which documents to get, and how to avoid double contributions or gaps in coverage.

Quick overview — the essentials

General rule: a worker is subject to the social security legislation of the country where they perform their activity.

Exception (posting): a Portuguese-employed worker or a Portuguese self-employed person may remain covered by the Portuguese social security system while temporarily working abroad — but only if the correct procedure (most importantly the A1/portable document) is requested and issued before the posting starts.

A1 (Portable Document): This is the official certificate that proves the worker remains subject to Portuguese social security during the posting. Employers or independent workers must request it from the ISS before departure.

Who does this apply to

Employees (TCO — Trabalhadores por Conta de Outrem): workers sent by their Portuguese employer.
Self-employed (TI — Trabalhadores Independentes): independent professionals who normally work in Portugal but will carry out temporary activity abroad.
Members of statutory bodies (MOE) or other special categories, when they carry out activities in two or more member states.

Which countries are covered / special cases

EU / EEA / Switzerland: the EU coordination rules (Regulation 883/2004 and 987/2009) apply. The A1 is the typical certificate.

United Kingdom: special arrangements since Brexit — there are two relevant frameworks: the Withdrawal Agreement (for postings started before 31 Dec 2020) and the Trade and Cooperation Agreement (for postings from 1 Jan 2021). A1 requests for the UK are made online. Note: extensions for the UK are generally limited to 24 months.

Countries with bilateral/multilateral social security agreements: Portugal has specific agreements with countries such as Brazil, the USA, India, Canada (Ontario & Quebec), several Ibero-American states, Morocco, Tunisia, etc. Those agreements define maximum posting durations and specific forms. Example: postings to Brazil may allow up to 60 months for employees (TCO) and 24 months for self-employed (TI).

Countries without any agreement: posting may still be possible, but additional rules can apply: short postings (≤ 12 months) have a simplified regime; longer postings (> 12 months) require a request to the ISS’s International Coordination Unit proving the activity remains temporary.

Duration rules & exceptions

Default maximum for EU/EEA/Switzerland/UK: 24 months. In exceptional cases and by agreement, it may be extended (some bilateral agreements or specific country rules permit longer periods).

Bilateral agreements: durations vary widely — some allow 12 months (extendable), others 24, 36, 48, or 60 months depending on the country and whether the worker is an employee or independent. Check the country-specific table in the ISS guide when planning a posting.

Step-by-step: What employers must do (before, during, after)

Before posting (must-do checklist)

Decide posting type: employee (TCO) or self-employed (TI).
Check the destination country: EU/EEA/Switzerland/UK / bilateral convention / no agreement — this determines procedure and maximum duration.
Obtain sufficient insurance — mandatory coverage for work accidents for the destination country for the entire posting period (policy or insurer statement).
Request the A1 / country-specific certificate from Social Security (ISS) before the posting starts. For most EU countries and the UK, this is the Portable Document A1. Submit the application online via the Social Security portal (Balcão e-Clic) or in person/by mail to the district centre.
Collect supporting documents: employment contract, pay slips, company registration/licences (if applicable — e.g., temporary work agencies or construction), residency permits for non-EU nationals, VAT/receipts for independents, and insurer statements.

During the posting

Carry the certificate (A1) as proof of Portuguese social security coverage and present it whenever required by host-country authorities or employers.

Respect host-country employment rules: minimum wage, working hours, health & safety, and equal treatment. Posting does not exempt you from complying with local mandatory employment conditions.

Notify ISS of changes: if the posting ends early, if the worker transfers to a different employer, or if residence changes.

After the posting

If the posting finishes on its scheduled date, nothing extra is usually required beyond maintaining records — but inform Social Security if the worker returns early or the employment ends earlier than planned.

Step-by-step for self-employed workers

Confirm you are normally insured in Portugal (have been paying social contributions). If you started the activity less than a year ago and you are not yet contributing, request early registration.
Request the A1 (or country-specific certificate) as proof to continue coverage in Portugal. Prepare VAT receipts, recent invoices, declaration of start of activity, and insurer statement for work accident coverage.
If posting > 12 months to a country without an agreement, you must request authorization (form RV 1024 in some cases) or obtain special authorization from the ISS’s International Coordination Unit.

Special topics & common scenarios

Telework / remote work

Teleworking is generally NOT considered posting. Social security is applied in the country where the worker is physically working. However, for telework involving companies established in the EU/EEA/Switzerland/UK and where written agreements exist, and if the period is < 24 months, an A1 might be possible — only when all legal conditions are met. If in doubt, request guidance and the A1 from ISS.

Drivers & cross-border transport workers

Drivers who operate in two or more EU Member States are a special case. Companies should request A1s for these workers because they regularly work across borders. (Regulation reference in the ISS guide.)

Brexit & the United Kingdom

Postings to the UK are still possible. Use the Withdrawal Agreement only for postings started before 31 Dec 2020 (and then seeking prolongation), and the Trade & Cooperation Agreement (TCA) for postings started on/after 1 Jan 2021. A1 applications for the UK are handled online. Extensions beyond 24 months for the UK are generally not possible.

Documents you will commonly need

A1 / Portable document (or country-specific certificate).

Proof of work accident insurance covering the period and territory of the posting (policy or insurer statement).

Employment contract (or service contract for independents).

Company licence (if the employer is a temporary work agency or in sectors like construction, where licenses are required).

Residency/authorisation documents for non-EU nationals.

Fiscal documents (VAT declarations, invoices, receipts for independents).

Rights and duties, what workers should expect

Rights: the posted worker retains Portuguese social security rights (contributions continue in Portugal) and must receive the host country’s mandatory protections (minimum wage, working time, health & safety, anti-discrimination).

Duties: continue paying contributions in Portugal (as required), keep the posting certificate available, and notify ISS of any material changes (early return, employer change, address change). Employers must handle declarations, secure insurance, and keep accurate records.

Country-specific forms & durations

The ISS guide contains a table listing many bilateral/multilateral conventions with each country’s maximum posting duration and the form name to be issued for the worker (for example, BR/PT 1 for Brazil, PT/AR 1 for Argentina forms, etc.).

Always consult that table before planning long postings — it’s the quickest way to find whether a country allows longer terms or needs a different certificate.

Practical HR checklist

Before posting

Confirm destination country category (EU / EEA / Switzerland / UK / bilateral / none).
Request an A1 or country-specific certificate from ISS.
Buy/prove accident insurance valid in the destination.
Gather contracts, licenses, and residency permits (if required).

During posting

Ensure the worker carries a certificate.
Adhere to host-country mandatory employment rules.
Keep communication open with ISS if any change occurs.

If posting extends beyond> country limit

Apply for extension/exception via ISS UCI (International Coordination Unit) with supporting justification.

Frequently Asked Questions (selected)

Q — Can I be covered by Portuguese social security and the host country at the same time?

A — If there’s a convention with the country, only one legislation applies (usually just one — the origin country if A1 is in force). If no convention exists, you may end up having to contribute in both countries; check the host country’s local rules.

Q — I lost my posting certificate. What now?

A — Contact the institution that issued it (ISS) and request a duplicate or second copy.

Q — I work remotely (teleworking) from another country — is that posting?

A — Generally, no. Telework is governed by the country where the worker physically performs the job. However, under specific written agreements and limited conditions, it can be treated as posting (especially for EU/EEA/Switzerland/UK and for periods below 24 months). Ask ISS if unsure.

Final tips & next steps

Plan early. Request the A1 well before the start date — processing and supporting documents take time.

Document everything. Keep insurer statements, contracts, invoices, and the A1 in a central HR file. This reduces risk in inspections or disputes.

When in doubt, ask ISS or a specialist. For postings longer than standard limits, multi-state work patterns, or complex telework arrangements, consult the ISS Unit for International Coordination.