Do any work at all in a foreign country and you may trigger social security obligations there. It is one of the most overlooked parts of an international move, and one of the most common questions we get.

Do any work at all in another country and you may trigger social security obligations there. It happens quickly, sometimes from the first day.

Most people focus on income tax when they plan a move. Social security receives far less attention, and it catches people out just as often.

In our latest video, Simon Roue and Laura Sant explain what to check before you go.

Where the rules come from

Social security operates separately from income tax. Different rules, different agreements, different paperwork.

If you leave the UK on assignment while remaining with a UK employer, three sets of rules apply. Which one governs your position depends entirely on your destination.

Get this right and you contribute in one country. Get it wrong and you may contribute in two, or find gaps in your record years later.

Going to the EEA

The post Brexit arrangement preserved a reciprocal agreement covering EEA countries.

Obtain the right certification and you remain within UK National Insurance while you work there. That certification is the A1 certificate.

Apply for it before you travel. Sorting the position out afterwards takes considerably longer.

Countries with a reciprocal agreement

Outside the EEA, the UK holds separate agreements with a limited number of countries. Canada, the United States and Japan sit among them.

The list is shorter than most people expect. Where an agreement exists, you can generally obtain a certificate of coverage, which keeps you inside UK National Insurance and out of the other country's system.

Check whether your destination appears on that list before you assume you are covered.

Everywhere else

For the rest of the world, no agreement exists. The other country may require contributions from your first day there.

Meanwhile, UK National Insurance continues for 52 weeks from the date you leave. After that period ends, you should drop out of the UK system. Your employer should also stop paying employer's National Insurance for you at that point.

Watch for that second point. Employers occasionally continue paying beyond the 52 weeks without noticing.

The 52 week rule works both ways

The same grace period applies on arrival in the UK.

Simon experienced this himself. Moving from Singapore, he stayed on Singapore payroll for twelve months before his employer moved him onto UK payroll, because UK National Insurance then applied.

One condition governs the whole thing. The grace period depends on you remaining with an employer based outside the UK. Take a UK local role instead and UK National Insurance starts straight away.

Check before you move

Social security can become tricky quickly, particularly when assignments extend, plans change or employment arrangements shift mid-move.

The right time to establish your position is before you travel. Certification is straightforward to obtain in advance and awkward to arrange retrospectively.

If you are planning an international move, or you have already made one and want to check where you stand, book a consultation at lsrpartners.com.

LSR Partners help you pay the right tax in the right place at the right time.

This article is for general information purposes only and does not constitute tax advice. Please contact us to discuss your specific position.