Which form for which case?
Unlike the uniform EU A1 certificate, the United Kingdom has no single standard form for overseas postings. HMRC distinguishes by destination country and employment type across four separate procedures:
- CA3822 – employees posted to the EU, EEA or Switzerland
- CA3837 – self-employed individuals working in the EU, EEA or Switzerland
- CA8421 – employees who work in two or more countries at the same time (UK plus EU/EEA/Switzerland)
- CA9107 – postings to a third country with which the UK has a bilateral social security agreement
Which form applies therefore depends first on the destination country and only then on employment status.
CA3822: employees in the EU, EEA and Switzerland
According to GOV.UK, form CA3822 is for employees "temporarily in an EU country, Gibraltar, Iceland, Liechtenstein, Norway or Switzerland" – making it the UK's functional equivalent of the A1 certificate. Key points from the official guidance:
- Applications can be made up to 12 months in advance ("You cannot apply more than 12 months in advance").
- The employer must first confirm eligibility with HMRC via the separate form CA3821 – only required once.
- Since 9 May 2024, the sending employer's PAYE reference number is a mandatory field.
- Since 1 December 2023, applications are online-only; the paper option has been removed.
If resident in an EEA state, Iceland, Liechtenstein, Norway or Switzerland, HMRC may also issue a healthcare entitlement certificate (S1) alongside the A1, covering access to local healthcare.
CA3837: self-employed in the EU, EEA and Switzerland
Self-employed individuals working temporarily in the EU, Gibraltar, Iceland, Liechtenstein, Norway or Switzerland use the separate form CA3837. The same 12-month lead time applies. The key difference from CA3822: HMRC explicitly checks whether the UK business is maintained during the overseas activity – for example through a continuing office, retained equipment, ongoing registration, and continued advertising of the UK business. Without this evidence, social security responsibility typically shifts to the host country.
CA8421: multi-state workers
Anyone who works regularly in two or more countries rather than on a single temporary posting – the UK plus at least one EU/EEA/Switzerland country – needs form CA8421 according to GOV.UK. It covers cases such as:
- Living in the UK, working in two or more countries (UK, EU, Gibraltar, Iceland, Liechtenstein, Norway, Switzerland)
- Living in one of these countries, working exclusively in the UK
- Flight or cabin crew with a home base in the UK
- Pure status evidence, for example if you still rent out property or hold a professional registration in the EU while living and working only in the UK
CA8421 is therefore broader than CA3822 – it is not about a single posting, but about ongoing clarification of which country's social security legislation applies when work happens in parallel across multiple countries.
CA9107: third countries with a social security agreement
For assignments outside the EU/EEA/Switzerland coordination framework, CA9107 applies – the UK's Certificate of Coverage, also called a "Certificate of Continuing Liability." According to GOV.UK, it applies only to a fixed list of countries with a bilateral agreement: "Barbados, Bermuda, Canada, Chile, Guernsey, India, Israel, Jamaica, Japan, Jersey, Mauritius, the Philippines, Republics of former Yugoslavia [...], South Korea, Turkey, USA." Employers, employees, self-employed individuals and authorised agents can all apply.
Recent legal change: On 7 July 2026, HMRC officially added India to the CA9107 country list ("The list of social security agreement countries has been updated to add India to the list of countries"). A special waiting period applies for India: a new Certificate of Coverage can only be requested at least 6 months after the previous India posting ended; if the previous posting was shorter than six months, the gap must be at least as long as that previous posting.
Comparing the four forms
| Form | Applies to | Scope | Lead time |
|---|---|---|---|
| CA3822 | Employees | EU, Gibraltar, Iceland, Liechtenstein, Norway, Switzerland | up to 12 months in advance |
| CA3837 | Self-employed | EU, Gibraltar, Iceland, Liechtenstein, Norway, Switzerland | up to 12 months in advance |
| CA8421 | Multi-state workers | UK + EU/EEA/Switzerland simultaneously | no fixed deadline |
| CA9107 | Employees, self-employed | Third countries with a UK social security agreement (incl. Canada, India, Japan, South Korea, USA) | no fixed deadline, but country-specific rules (e.g. India, Norway) |
Processing time and deadlines
GOV.UK itself does not state a fixed processing time for any of the forms. UK accountancy and tax advisory firm AAB (Anderson Anderson & Brown) describes the practice as follows: "There is no agreed timescale, and it can vary from a few weeks to a number of months, for an application to be processed and a certificate issued." Retrospective applications are usually unproblematic according to AAB, provided the person qualifies – with one important exception: "for certain countries a time limit does apply [...] for example for UK postings to Norway the application needs to be made within 4 months of the first date in Norway." A CA3822 certificate typically covers up to 24 months, and a CA9107 Certificate of Coverage up to five years, depending on the specific agreement.
What this means for employers
For companies with UK employees on overseas assignments, the takeaway is: it's not enough to apply for "an A1 form" – first you need to establish whether the destination falls under EU/EEA/Switzerland coordination (CA3822/CA3837/CA8421) or a bilateral agreement (CA9107), and whether the person is employed or self-employed. Since GOV.UK does not commit to a fixed processing time and individual countries set their own deadlines (as with Norway), early and systematic deadline tracking is advisable. Tools like premote help automatically detect country-specific certificate requirements such as the UK's four HMRC procedures alongside the A1 certificate, and keep deadlines on track.
FAQ
Is there an A1 form in the United Kingdom?
Not literally. For EU/EEA/Switzerland postings, CA3822 (employees) or CA3837 (self-employed) perform the function of the A1 certificate; for third countries with an agreement, CA9107 applies.
Which form applies for a posting to the USA, Canada or India?
CA9107 – the UK's Certificate of Coverage for countries with a bilateral social security agreement. India has officially been on the country list since 7 July 2026, with an additional 6-month waiting period between two postings.
How far in advance can CA3822 or CA3837 be applied for?
Up to 12 months before the overseas assignment begins.
How long does HMRC take to process an application?
GOV.UK does not state a fixed deadline. According to advisory firms such as AAB, it can take anywhere from a few weeks to several months depending on the case – early application is recommended.
Are there countries with a special application deadline?
Yes. For postings to Norway, AAB notes the application must be made within four months of the first day worked in Norway – an exception to the otherwise more flexible timing.
The information provided on this website does not constitute legal advice and is not intended to address any legal issues or problems that may arise in individual cases. The information on this website is of a general nature and is provided for informational purposes only. If you need legal advice for your individual situation, you should seek the advice of a qualified attorney.