UK to USA Mobility: What Employees Need to Do Before They Move

Most advice on moving to America is about boxes, schools and driving licences.

Those matter, but they are logistics. Mobility is the set of decisions underneath, and they decide what you keep, what you lose and what you can undo.

Your employer is making some of these decisions now. Many employees only learn the consequences after they have signed.

What does mobility mean for an employee moving from the UK to the USA?

Mobility covers every decision about how your employment, pay, pension and benefits change when you move country. It is separate from the practical relocation.

Nine questions drive it. Work through them in order, because the early answers limit the later ones.

Is your move an assignment or a permanent transfer?

The two look similar in an offer letter and work very differently.

An assignment is temporary. You usually stay on UK terms, receive allowances, and expect to return. A permanent transfer moves you onto US terms with no return built in.

Many assignments end in a third step called localisation. That is when you stop being an assignee and become a local US employee, usually without the allowances.

Ask your employer to state three things in writing. These are the intended type of move, the planned length, and the trigger for any localisation.

Ambiguity here causes more disputes than any other mobility point. Assignments drift into permanence at renewal, and the allowances quietly stop.

Who will be your legal employer in the USA?

Your employer has two realistic options. You stay on your UK contract, or you move onto the payroll of a US company in the group.

Your visa category decides which entity can employ you. Confirm the structure with your immigration attorney before you sign anything, and do not agree to a different employer without that check.

Staying on a UK contract while living in a US state can create tax and compliance exposure for your employer. Expect longer stays to move onto US terms.

Ask who your employer is, who runs your payroll, and who to call when something goes wrong.

Which country’s employment law will protect you?

Do not assume UK employment rights follow you abroad. Ask which country’s law governs your contract and whether UK statutory protections still apply, and get the answer in writing.

In the UK, you need two years of service to claim ordinary unfair dismissal, according to Acas. That is due to change to six months from January 2027, but it is not yet law.

Almost every US state allows at-will employment. Either side can end the job at any time, for any lawful reason, usually without notice. Montana is the exception, requiring good cause once a probationary period ends.

Our guide to at-will employment exceptions explains where US protection does apply. Discrimination and retaliation are two examples.

Moving onto US terms generally means trading UK dismissal protection for at-will employment. Weigh that before you accept a permanent transfer.

Does your length of service carry over?

Your service date underpins several UK rights. Notice periods, redundancy pay and unfair dismissal protection all depend on it.

A fresh US contract can reset that date. The change often looks like administrative tidying, which is why people miss it.

Ask your employer to recognise your original start date in writing. It costs them little now and avoids an argument later.

This matters most if you might return to the UK business. A reset date means you rebuild those rights from zero.

How will your pay and relocation package work?

Check the currency, the payroll location and the frequency. Many US employers pay fortnightly or weekly rather than monthly, so ask when your first payment will arrive.

Ask what the package includes. Common items are flights, shipping, temporary housing, a settling-in allowance and a cost-of-living adjustment.

Look for a clawback clause. It requires you to repay part of the package if you leave within a set period.

Then ask about tax equalisation. Under this approach, your employer covers the extra tax cost of the move so you pay roughly what you would have paid at home.

Employer-paid relocation reimbursements are generally taxable US wages, according to IRS Publication 15-B. Your UK tax residence also changes when you leave, and HMRC’s Statutory Residence Test decides it. Take advice from a cross-border tax adviser before you rely on any gross figure.

What happens to your social security and pension?

Two systems hold two separate records, and gaps in either are hard to repair.

Your UK State Pension record

The full new State Pension is £241.30 a week and needs 35 qualifying years of National Insurance, according to GOV.UK.

Years worked in America do not add UK qualifying years. Check your record online before you leave so you know where the gaps are.

The rules on voluntary contributions changed on 6 April 2026. Most people can no longer pay Class 2 contributions for time abroad.

Class 3 remains, but you now need 10 years of UK residence in a row or 10 years of qualifying contributions, according to GOV.UK. The previous threshold was three years. You apply using form CF83.

Existing voluntary Class 2 payers can apply for Class 3 without meeting the 10-year test if they apply before 6 April 2027.

The certificate of coverage

The UK US social security agreement can keep a temporary assignee in the UK system. You then avoid US Social Security and Medicare tax during the assignment.

The SSA says the US work must be expected to last no longer than five years. Your employer requests the certificate from HMRC and gives it to the US payroll team, so ask early.

Without one, you pay US payroll taxes. The IRS sets the employee rates at 6.2% for Social Security and 1.45% for Medicare, a combined 7.65%.

Social Security stops at $184,500 of earnings in 2026, according to the IRS. Our guide to FICA explains each element.

Your UK workplace pension

Your workplace pension stays where it is unless you move it. Transferring it to an overseas scheme can trigger a 25% overseas transfer charge, according to GOV.UK, so take specialist advice first.

Update your address with the provider and keep your login details safe. Ask whether your employer will make contributions on your behalf while you are away.

What happens to your bonus and share options?

Rewards that vest over several years need a plan before you move. Ask how each one will be taxed in the UK and the USA if you leave mid-vest.

Ask what happens to unvested options, bonus eligibility and long-term incentives when you move. Ask whether the scheme rules change if your employer changes.

Share scheme tax treatment depends on the plan type and your residence at each vest. Get a cross-border tax adviser to review it before you move, not at the next vest.

Which benefits replace your UK ones?

Several UK benefits are tied to your UK contract and stop when it does. Death in service, income protection and private medical cover are usually written for UK employees.

Check each policy’s territorial limits rather than assuming it continues.

Healthcare

Healthcare is the largest change. Cover usually comes through your employer, and you pay part of the cost.

In 2025, average annual premiums for employer cover were $9,325 for single and $26,993 for family cover. Workers paid an average of $1,440 and $6,850 of that, according to KFF.

The average single-cover deductible was $1,886, and 34% of covered workers had a deductible of $2,000 or more. Compare deductibles, co-pays and out-of-pocket limits, not just the premium.

A group health plan cannot impose a waiting period longer than 90 days, according to the Department of Labor. Ask when your cover starts and arrange private international cover for any gap.

Holiday

UK workers on a five-day week are entitled to at least 28 days of paid leave, according to GOV.UK. Employers can count bank holidays within that.

US federal law requires no paid vacation at all. Your allowance is company policy, so agree it before you sign. Our guide to paid time off in the USA covers typical levels.

Retirement savings

A 401(k) replaces your UK workplace pension. For 2026 you can contribute up to $24,500, with an $8,000 catch-up from age 50 and $11,250 at ages 60 to 63, per the IRS.

Employer matches can vest over time, under cliff or graded schedules. On a short assignment, check the schedule, as you may leave before the match becomes yours.

What happens when the move ends?

Assignments end, and few contracts say what follows. Silence usually means you have no right to return.

Ask five questions before you go.

• Is there a role waiting for you, and at what level?
• What if the UK business reorganises while you are away?
• Who pays to bring your family home?
• Does your service date resume on return?
• What happens if the US role ends first?

Get the answers in the assignment letter, not in a conversation.

What do you need to do before you leave the UK?

Once the structure is agreed, deal with the UK admin.

• Tell HMRC you are leaving. If you do not file Self Assessment, this usually means form P85, with parts 2 and 3 of your P45. HMRC then checks whether you are owed a refund.
• Keep a UK bank account. HMRC refund cheques generally need one, so check your bank’s rules for non-residents.
• Check your National Insurance record. Decide on Class 3 voluntary contributions while you still qualify.
• Collect your records. Get medical, dental and vaccination history, and a no-claims letter from your car insurer.
• Carry enough medication. Bring supplies to cover the weeks before a US doctor can see you.
• Review UK benefits you claim. Contact the relevant office before you leave.
  
  

What do you need to do after you arrive?

The first fortnight is paperwork. Each step unlocks the next.

Complete Form I-9 and your tax forms

Every new US employee completes Form I-9 to confirm identity and right to work. You complete Section 1 by your first day of paid work, and your employer completes Section 2 within three business days.

Bring original documents, usually your passport and immigration papers.

You also complete Form W-4, which tells your employer how much federal tax to withhold. Our Form I-9 guide covers the process.

Apply for a Social Security number

You need a Social Security number for payroll, banking, credit and most leases. The SSA suggests waiting 10 days after arrival so your immigration records can be verified.

You apply in person with your passport and US immigration documents.

Build a credit history

Your UK credit score does not transfer, so you start from zero. That affects renting, car finance and phone contracts.

A secured credit card, paid in full each month, is the usual first step. A letter from your employer confirming salary and start date helps with landlords.

Get a US driving licence

Driving rules are set by each state, not by the federal government. Check your state’s rules as soon as you know where you are moving.

California, for example, requires holders of non-US licences to pass both a knowledge test and a driving test. Book early, as test appointments can be hard to find.

Settle your household

Your partner’s right to work depends on your visa category, so raise it with your immigration attorney at the start. Public school places are generally assigned by district, so check the district before you sign a lease.

Our US business culture guide covers what to expect in a US team.

The UK to USA mobility timeline for employees

The mobility mistakes we see most

Assuming the UK contract travels. Leaving it in place while you work in a US state creates exposure for you and your employer.

Losing your service date. A new US contract can wipe out years of accrued rights without anyone saying so.

Ignoring the State Pension record. The gap only appears at retirement, when it is too late to fix.

Not asking about return rights. A verbal promise of a role to come back to is not a right.

Does your company have a US employer ready?

For most transferring employees, the employer is a US company in your group. If you do not have one yet, it needs to exist before the employee’s start date.

Foothold America sets up US entities for UK and European companies. We file the C-corporation or LLC with the state, obtain the EIN, appoint a registered agent and refer you to banking partners.

We also offer Cultural Intelligence Advisory, which helps teams bridge US cultural gaps in the workplace.

Planning a move in the next six months? Tell us the state, the role and the start date, and we will work out the entity steps against your timeline.