A1 certificate: keeping UK workers in UK National Insurance in the EU, EEA and Switzerland

When someone from the UK works in an EU country, the default is that social security contributions are paid there, not in the UK. The A1 — HMRC calls it a certificate of coverage, or PDA1 — is the document that keeps a temporarily posted worker in UK National Insurance instead, for up to 2 years. It is applied for online, and it is not a work permit. This page sets out HMRC’s own wording on who qualifies, how to apply, and what the certificate does not do.

Who needs an A1, situation by situation

The table is deliberately narrow. HMRC’s guidance lists specific situations in which a certificate can be issued; anything outside those lists falls back to the default — contributions where the work is done — unless the two countries agree otherwise.

The default, and the exception

HMRC starts from a single principle:

The certificate is the exception, and HMRC describes it precisely:

For employers there is one more line that matters: “If you’re an employer, your liability to pay social security contributions will follow the liability of the employee concerned.” An employer that sends someone to Germany without a certificate may find it has German contributions to pay, not just the employee.

The two-year posting

The case most businesses need is the temporary posting. HMRC lists it first:

Four conditions sit inside that sentence, and each can fail on its own:

• Employed in the UK — the person is already on the UK payroll.
• By an employer who normally carries out its activities in the UK — the employer’s own business has to be here.
• Temporarily, for up to 2 years — a permanent move does not qualify.
• Sent, or agreed to, by the employer — a worker who decides to work from a holiday home is a different case.

The self-employed have a parallel route: “self-employed in the UK and you’re going to carry out a similar activity temporarily in an EU country, for up to 2 years”. Their form, CA3837, asks whether they are “if you’ll be maintaining your UK self-employment whilst working abroad” — keeping an office, equipment, registration or advertising in the UK.

Longer than two years

A posting that runs past the allowed period is not automatically outside UK National Insurance, but it is no longer a matter of right: “HMRC and the social security authority in the EU country can agree to this, but will only do so in exceptional circumstances.” The application needs a signed statement explaining why staying in UK National Insurance is in the worker’s best interest.

Other situations HMRC lists

• Multi-country workers: “working in the UK and one or more EU countries, at the same time”.
• Aircrew: “working as a flight or cabin crew member, where your home base is in the UK”.
• Civil servants working for the UK government in an EU country.
• Seafarers on vessels, in several combinations of flag, residence and employer.

Iceland, Liechtenstein, Norway, Switzerland and Gibraltar

These are covered by separate agreements, but HMRC describes the same core route: an employee or self-employed person “you’re going to work temporarily in either Gibraltar, Iceland, Liechtenstein, Norway, or Switzerland for up to 2 years” can apply for a certificate. The list for these countries adds workers on the Norwegian continental shelf.

How to apply

1. Employer eligibility, once. “Your employer must have confirmation from HMRC that their business is eligible to apply for a certificate.” “Your employer can ask HMRC to confirm their eligibility using form CA3821. We will only need to confirm their eligibility once.”
2. Collect the details. Place of birth, nationalities, previous names and “the PAYE (Pay As You Earn) reference number of the employer sending you to work abroad”.
3. Apply online on CA3822. “You cannot apply more than 12 months in advance.”
4. Add a signed statement if needed. “If you’re applying for a certificate of coverage for a period longer than allowed, you’ll need to attach a signed statement.”
5. Agents need authority: “If you’re an agent working on behalf of your client, your client needs to fill in an authorising your agent (64-8) form.”

If the worker will live in the other country, the same application can lead to healthcare cover funded by the UK: “HMRC will consider whether you qualify for UK funded healthcare, and if you do, HMRC will also issue you with a healthcare entitlement certificate (S1).”

What an A1 does not do

It settles one question — which country’s social security scheme applies. It does not settle the others:

• Permission to work is an immigration question for the country of work. How long a UK passport holder may stay in the Schengen area at all is on the Schengen 90/180 rule.
• Income tax is separate from National Insurance and is not decided by the certificate.
• Employment rules: GOV.UK says that if you are sent to work abroad temporarily, “your employer must follow some of the employment rules of the country you’re sent to work in”.

Short business trips

HMRC’s guidance is written around people going “to work” in another country and does not separately address a one-day meeting or a conference visit. Whether a host country expects a certificate for short trips is a matter for its national rules, which we have not read at source, so we do not summarise them. For a regular pattern of short trips by the same person, the multi-country category above is the one to check with HMRC’s form-finder tool.

For the travel policy

• Separate trips from postings. A posting triggers a certificate question; a meeting usually does not.
• Make someone responsible for applying before the work starts, within the 12-month window.
• Track the 2-year clock per person, and the extension route if it will be exceeded.
• Keep the certificate where the traveller can show it.

Visitors coming the other way are covered on UK business visitor rules, and the employer’s wider obligations on duty of care. This page reproduces HMRC’s guidance as read on 2026-09-25; it is not tax or social security advice.

Common questions