Granting US stock options to UK employees: get it right
Granting US stock options to UK employees sounds like an easy decision. After all, equity is a powerful way to attract talent, build loyalty and drive long-term value, especially for fast-growing US companies expanding overseas.
But there’s a catch. What works in the US doesn’t always work in the UK. In fact, assuming the rules are the same is one of the easiest ways to trip up. Different tax rules. Different legal requirements. Different reporting obligations. Assuming they’re the same is one of the most common (and costly) mistakes we see.
Here we cover the key things to get right from the start if you’re granting US stock options to UK employees.
1. UK tax rules are different
In the UK, tax treatment depends on:
- whether the option is under a tax-advantaged scheme, like enterprise management incentives (EMIs);
- the group structure (especially who employs the individual);
- the employee’s tax residency.
Standard US options or RSUs, when granted to UK employees, often lead to:
- income tax and national insurance contributions (NICs) on the spread at exercise;
- “dry” tax charges when RSUs vest if there is no liquidity in the company’s stock;
- a potential PAYE withholding obligation for the UK employer;
- Capital gains tax (CGT) on future growth from exercise to sale.
2. UK tax-advantaged options can offer big tax savings
The UK has two HMRC approved tax-advantaged option regimes: EMIs and Company Share Option Plan (CSOP).
If your UK entity qualifies, EMIs are attractive for the following reasons:
- No income tax or social security (NIC) if the strike price is at least equal to the market value at grant.
- Only CGT on disposal, potentially at a 14% rate with business asset disposal relief (18% from 6 April 2026).
However, EMIs aren’t open to everyone. The group must:
- have <250 employees and <£30 million gross assets;
- carry on a qualifying trade;
- employ the individual for more than 25 hours a week (or 75% of their time); and
- have a UK permanent establishment.
There are additional conditions that need to be met.
EMI options must be reported to HMRC within 92 days of the end of the UK tax year (i.e. 6 July). If the company does not qualify for EMI, CSOP options offer similar benefits, but can be less flexible for the employer and employees.
3. Who the employer is really does matter
Even if the US parent grants the options, UK tax obligations often sit with the UK employer, especially if the stocks are ‘readily convertible assets’ (RCAs). That can mean:
- PAYE and NICs withholding obligations for the UK entity;
- employer NICs liability, possibly without recharge from the US parent.
If there’s no recharge mechanism, the UK entity could be left footing the bill.
Using a PEO or EOR creates further complications for both the economic employer, i.e. your UK business, and the employee, which can create an involved and expensive compliance risk if it’s not planned for. Using a PEO or EOR also means your company often won’t be eligible to grant UK tax-advantaged options such as EMIs.
4. Don’t forget HMRC reporting
The UK employer must report all share-related events (grants, lapses, exercises, disposals) each year through the Employment-Related Securities (ERS) return.
- the plan must be registered with HMRC;
- annual ERS returns are due by 6 July after the UK tax year ends;
- penalties apply for missing filings.
Failure to report can jeopardise tax treatment and trigger penalties.
5. Cross-border complications
If UK employees have international roles or are mobile or if non-UK employees spend time in the UK:
- dual tax residence and split-year treatment can affect liabilities;
- you may need to apportion gains based on workdays;
Some countries won’t credit UK tax leading to double taxation.
Robust tracking and coordination are vital for global teams.
6. Valuations: 409A ≠ UK market value
US groups often rely on 409A valuations, but HMRC won’t always accept this, especially for EMIs.
- for EMI grants, it’s best to agree a valuation with HMRC in advance;
- UK subsidiaries can affect the overall group value.
Valuation differences can impact tax treatment and scheme eligibility.
7. Pitfalls of granting US stock options
Even if US corporate approvals aren’t needed, UK rules still apply:
- offering shares to UK staff may need FSMA exemptions;
- leaver provisions and employment rights differ under UK law;
- documents should be tailored for UK employees and compliant with data protection laws.
Therefore, key tasks for legal, HR and finance teams include:
- identifying eligible UK employees and assessing EMI feasibility;
- coordinating with the US on timing, valuations and paperwork;
- making sure the UK employer understands PAYE/NICs duties;
- registering with HMRC and prepare for ERS reporting;
- taking legal and tax advice to ensure alignment across borders.
8. Accounting: don’t forget the UK books
Even if the US handles group accounting, UK entities usually report under IFRS or UK GAAP (FRS 102).
They need to:
- record a P&L charge over the vesting period;
- credit equity (or a payable, if there’s a recharge);
- measure options at fair value on grant date, using models like Black-Scholes.
If the cost is recharged:
The UK entity may record a liability, not equity;
- VAT may apply depending on structure;
- make sure intercompany documentation is in place.
Deferred tax may also come into play, especially if the tax deduction exceeds the accounting expense.
Local finance teams need to coordinate with the US parent. Option grants, vesting and modifications must be tracked locally because share-based payments can have a real impact on the UK statutory accounts. This includes disclosures, the impact of the charge on profit or loss and the impact on tax in the accounts – all of which will be subject to audit.
9. Corporation tax: what’s deductible?
Even if the UK company doesn’t issue the stock or book the expense, it can usually claim a corporation tax deduction under UK rules, based on the gain at exercise (not the share-based payment expense).
- tax deduction = market value at exercise minus exercise price;
- applies even if there’s no recharge from the US;
- especially generous for EMIs and CSOP options where no income tax or NICs are due.
Be wary of:
- no deduction if the gain isn’t taxed as employment income;
- no deduction if the shares are issued in the UK subsidiary rather than the parent company;
- HMRC may deny the deduction if the employee’s UK duties aren’t clear.
Key tasks for the tax team:
- monitor share option exercises and ensure gains are appropriately linked to UK employment;
- assess the need for tax elections, such as a Section 431 ITEPA election or an agreement to transfer employer NIC liabilities to the employee;
- secure a corporation tax deduction for employer NIC by crystallising the liability at the right time;
- review and adjust deferred tax positions to reflect temporary differences between accounting and tax treatments.
Final thoughts on granting US stock options to UK employees
Stock options are advantageous but can be costly if mishandled.
Offering US equity to your UK team can be a good way to drive loyalty and long-term value. However, if the UK tax, legal and compliance landscape isn’t properly managed, things can unravel fast.
From EMI qualification and HMRC valuation to ERS filings and corporation tax relief, the details really matter. Not taking local advice is how valuable tax reliefs get missed and avoidable compliance problems take hold.
Help from the experts
We help international groups get their UK share schemes right, from initial design through to tax treatment, filings and ongoing compliance. Contact us to discuss how we can support your UK expansion and make sure your equity plans work on both sides of the Atlantic.
