Sent to Spain by a foreign employer, which contributions apply (A1 certificate)?

Key rules

• Maximum posting: A posting from an EU, EEA or Swiss state keeps you in your home system for up to 24 months, with an A1 certificate.
• Who issues the A1: The sending country's social security office issues the A1, not Spain.
• Prior cover: You must already be covered by your home system before you are posted, in practice for at least one month.
• No A1: Without an A1, Spain can require you to be registered and your employer to pay contributions, and can fine your employer.

Can you stay in your home system?

Yes, if you are sent to Spain from an EU, EEA or Swiss state and meet the conditions below. You keep paying into your home system for up to 24 months, and you prove it with an A1 certificate. You do not pay Spanish social security on top.

The conditions

All of these must be true:

• Your employer normally carries out substantial activity in the sending country, not just internal administration.
• You keep a direct employment relationship with that employer during the posting.
• You work for that employer's account.
• You were already covered by the home system before the posting. In practice, this means at least one month.
• You are not being sent to replace another posted worker.

The posting must be expected to last no more than 24 months.

How to get the A1

The A1 is issued by the social security office of the country sending you, not by Spain. Your employer usually applies, often online, before you start. You can also apply yourself.

The office checks the conditions and issues the certificate. Waiting times run from days to several weeks, depending on the country. Apply early.

Keep the A1 with you in Spain. Inspectors can ask to see it. The documents list and checklist below show what to prepare.

If the posting runs longer than 24 months

You cannot renew a posting so the same person replaces themselves. Spain and the sending country can agree an exception, usually for a defined period. Ask the sending country's office to request it from the Spanish authorities. Your employer or you can ask. Do this well before the 24 months end.

If you start work without an A1

Without an A1, you cannot prove you are still covered at home. Spanish authorities may treat you as subject to Spanish social security. That means registration and contributions through the Spanish social security treasury. Inspectors can fine your employer for failing to register you or pay contributions.

You can fix this by asking the sending country's office for an A1 with retroactive effect. Once you show it, the Spanish liability normally goes away.

Other forms

Healthcare and unemployment forms work differently from the A1. The FAQ below covers them.

Timeline and deadlines

• Be covered by your home social security system before you are posted: at least 1 month before the posting starts

• Employer applies for the A1 with the sending country's social security office, often online: before the posting starts

• Stay in your home system while the posting lasts: up to 24 months

Documents you need

• A1 certificate, issued by the social security office of the country sending you, not by Spain. It proves you stay in your home system for up to 24 months. Keep it with you to show Spanish authorities or inspectors on request.

• Proof that your employer carries out substantial activity in the sending country and that you were already covered by the home system, normally for at least one month before the posting. The sending country's office checks this before it issues the A1.

Checklist

• Confirm you keep a direct employment relationship with the sending employer and work for that employer's account.

• Check that you were already covered by the home system, normally for at least one month, and that you are not replacing another posted worker.

• Ask your employer to apply for the A1 with the sending country's social security office before you start in Spain, or apply yourself.

• Keep the A1 with you in Spain to show to inspectors on request.

• Ask the sending country's office for the A1 with retroactive effect if you are already working in Spain without one.

What to watch out for

• Working in Spain without an A1: Without an A1 you cannot prove you are still covered by your home system, so Spanish authorities may treat you as subject to Spanish social security and require registration and contributions. Ask the sending country's social security office for the A1 straight away. It can be issued retroactively, and once you show it the Spanish liability normally falls away.

• Fines for your employer: The Labour and Social Security Inspectorate can fine your employer for failing to register you or pay contributions in Spain. Get the A1 before you start work and keep a copy to show an inspector.

Quick answers on A1, U1 and S1 forms

What does an A1 certificate prove?

An A1 certificate proves which country's social security rules apply to you, so you pay contributions in one country only. Other countries' institutions must accept it while it is valid. In Spain, the TGSS (the social security treasury) issues it if you stay under Spanish cover while working abroad.

Who needs an S1 form for healthcare?

You need an S1 form if you live in one country while another country pays for your healthcare. This covers pensioners, cross-border workers, posted workers and their family members. The paying country's institution issues it. If you arrive in Spain with one, the INSS provincial office (CAISS) registers you for the Spanish public health service.

Do I still need a U1 document to claim unemployment benefit?

No, the paper U1 has been replaced by electronic documents that institutions exchange directly. The unemployment office of the country where you worked (SEPE in Spain) sends your work periods, so they count toward your claim in the new country.

Can I get my Spanish social security contributions refunded when I leave Spain?

No, Spanish contributions are generally not refunded when you leave. They count toward future Spanish pensions and may be added to periods from other countries. Refunds are limited to cases such as contributions paid in error or above the legal maximum.