EMI Options for a US Citizen: Section 409A and 83(b) Issues

EMI options for a US citizen are taxed on two separate tracks: the UK Enterprise Management Incentive scheme can remove Income Tax and National Insurance on exercise, but the IRS does not recognise it, so the spread at exercise is generally ordinary income on the US return. Section 409A can add a 20% penalty tax if the option was granted at a discount, and an 83(b) election usually does not apply to the option itself.

This guide is general information, not advice on your own grant. US/UK Cross Border Tax — US CPAs and UK tax advisers working as one team; London, Manchester, New York, San Francisco — advises founders and employees holding UK share options, and the right answer depends on your plan rules, your residence and your citizenship or green card status.

How are EMI options taxed for a US citizen?

An EMI option is taxed twice under two different rulebooks. The UK looks at whether the option qualifies under the EMI scheme, and the US looks at the option as a nonstatutory stock option. The United States taxes citizens and green card holders on worldwide income, and the saving clause in the US/UK treaty means a US citizen cannot use the treaty to switch off US tax on their own compensation.

On the UK side, GOV.UK states that you will not pay Income Tax or National Insurance when you buy shares at least at their market value when the option was granted, within the 10 or 15 years your option agreement sets. If you buy at a discount to that market value, you pay Income Tax and National Insurance on the difference. Capital Gains Tax can apply when you sell.

On the US side, IRS Topic 427 separates statutory options (incentive stock options and employee stock purchase plans) from nonstatutory options. An EMI plan is written to satisfy UK conditions, not section 422 or 423, so it is generally a nonstatutory option. For a nonstatutory option without a readily determined market value, the IRS says there is no taxable event at grant, and you include in income at exercise the market value of the stock minus what you paid.

Why UK tax-advantaged status does not carry over to the US

A tax-advantaged label in one country is a label in that country only. The IRS applies its own definitions, and EMI is not among them.

Event	UK treatment (EMI, option at market value)	US treatment (nonstatutory option)
Grant	No Income Tax or National Insurance	No tax where the option has no readily ascertainable market value
Vesting	No charge	No charge on the option; shares received later may be taxed on vesting if they are restricted
Exercise	No Income Tax or National Insurance if the price paid was at least market value at grant	Spread (market value minus price paid) is compensation income in the year of exercise
Sale	Capital Gains Tax on proceeds less the price paid; Business Asset Disposal Relief may apply	Capital gain or loss measured from the market value at exercise, which is the new basis

The difference matters most for a US citizen in the UK whose company grows quickly. If the shares are worth far more on exercise than the exercise price, the UK charge may be nil while the US charge is based on the whole spread, payable in dollars, often before any shares can be sold.

Our founder tax guide for a US/UK startup covers the company structure side. This post goes deeper on the option itself.

What happens at grant, vesting, exercise and sale?

The US taxable event for most EMI options is exercise, not grant or vesting. The reason is the regulation at 26 CFR 1.83-7: if an option has no readily ascertainable fair market value at grant, section 83 applies when the option is exercised, and the exercise is treated as a transfer of property.

Readily ascertainable value is a high bar

The regulation treats an option as having a readily ascertainable value if it is actively traded on an established market. Otherwise the taxpayer must show that the option is transferable, immediately exercisable in full, free of significant restrictions, and that its value can be measured with reasonable accuracy. An EMI option over private company shares is normally non-transferable, so it does not meet that test, which is why grant is not a US event. If an option did meet it, the rule flips: section 83(a) would apply at grant, so confirm the facts rather than assuming.

Exercise

At exercise the compensation is the fair market value of the shares received minus the price paid. The US value is not automatically the figure HMRC accepted for EMI purposes. HMRC valuations and US valuations answer different questions, and you need a defensible US value on the exercise date.

Sale

When you sell, IRS Topic 427 says the result is generally a capital gain or loss. Your US basis is the value taxed at exercise plus any price paid, so only growth after exercise is a fresh gain. On the UK side the base cost is just what you paid, which is why the UK gain is larger than the US gain whenever the exercise value exceeds the price.

Section 409A and EMI options: when is a UK option at risk?

Section 409A is the US deferred compensation law, and an option sits outside it only if it satisfies the stock right exclusion. Under 26 CFR 1.409A-1(b)(5), the exercise price may never be less than the fair market value of the underlying stock on the date of grant, the number of shares must be fixed at grant, and the option must not include any feature for deferring compensation beyond the deferral of income until exercise.

Three EMI features deserve a check against that rule.

1. Discounted options. The UK allows an EMI option to be granted with an exercise price below market value, with Income Tax and National Insurance charged on the discount at exercise. A US option with a below-market exercise price is generally deferred compensation, and the plan must then satisfy section 409A's timing and payment rules, which an ordinary option plan does not.
2. Valuation at grant. A UK company will often agree a share valuation with HMRC. That figure does not by itself prove US fair market value. If the US value at grant was higher than the exercise price, the option may have been granted at a discount without anyone intending it.
3. Later changes. Extending the exercise period, replacing an option on a reorganisation, or adding rights on an exit can be treated as a new grant or as an added deferral feature. Review any amendment against the regulation before it is signed.

The cost of failing is high. 26 U.S.C. 409A(a)(1)(B) adds a 20% additional tax on the amount included in income, plus premium interest at the IRS underpayment rate with an extra 1%, running from the year the compensation was first deferred or became vested. The inclusion generally happens before you can sell the shares.

Does an 83(b) election apply to EMI options?

An 83(b) election generally does not apply to an EMI option, because it applies to property that has been transferred to you, and an unexercised option is not that. Section 83(e)(3) says section 83 does not apply to the transfer of an option without a readily ascertainable market value, so there is no grant-date election to file.

An election can matter after exercise. If you exercise and receive shares that are still subject to vesting or forfeiture, for example under an early-exercise right or a company repurchase right, those shares are restricted property. Section 83(b) lets you include their value in income on the transfer date instead of on vesting. The election must be filed no later than 30 days after the transfer and cannot be revoked without IRS consent, and the IRS provides Form 15620 for it. If you do not file, tax falls on each vesting date at the then-current value, which can be much higher.

The 409A regulation states that receiving substantially nonvested stock on exercise is not, by itself, an additional deferral feature. The two rules therefore sit side by side: 409A tests the option, and 83(b) concerns the shares you acquire.

What about double taxation and the foreign tax credit?

The same economic gain is taxed by two countries in different years, and the foreign tax credit may not fully bridge the gap. A US citizen claims credit for UK income taxes on Form 1116, and the credit is limited to the US tax on income in the same category and from foreign sources.

Timing mismatch

The US taxes the spread at exercise. The UK taxes the gain, when there is one, at sale. If those are in different tax years, the UK tax paid at sale is not available as a credit against the earlier US tax unless it is carried within the credit rules. Our guide to the UK tax year versus the US tax year shows why even a same-day event can land in different years: the UK year runs to 5 April and the US year to 31 December.

Character mismatch

US ordinary income at exercise is matched by UK Capital Gains Tax, which is a different type of tax on a different base. The credit mechanism looks at the foreign tax on the same income, so you need to work through the numbers rather than assume a one-for-one offset. The foreign tax credit guide and our note on double taxation relief between the US and UK explain the mechanics.

Sourcing

The Form 1116 instructions say compensation other than fringe benefits is sourced on a time basis. If your services were performed in the UK over the period the option relates to, the exercise income is generally foreign source, which supports the credit. Time spent working in the US over that period moves part of the income into US source.

Illustrative example: one exercise, two tax bills

Illustrative example: all figures are assumptions for explanation only, not a forecast or advice. A US citizen resident in the UK holds 10,000 EMI options granted in 2024 with an exercise price of £1.00 a share, equal to market value at grant. In 2026/27 the company is sold, the options are exercised and the shares sold at £6.00 a share. Assumed exchange rate: £1 = $1.30. Assumed US federal marginal rate on the exercise income: 35%.

Item	UK (2026/27)	US
Cost to exercise	£10,000	$13,000
Value of shares	£60,000	$78,000
Income Tax and National Insurance on exercise	Nil (price equals market value at grant)	Not applicable
Taxable amount	Gain £50,000, less £3,000 annual exempt amount = £47,000	Compensation $65,000 (spread)
Tax at assumed rates	£8,460 if Business Asset Disposal Relief at 18% applies; £11,280 at 24% if it does not	$22,750
Capital gain on the same-day sale	Included above	Nil (basis $78,000 equals proceeds)

The UK rates used are those GOV.UK lists for 2026/27 (24% for higher-rate taxpayers, with a £3,000 annual exempt amount) and the 18% Business Asset Disposal Relief rate from 6 April 2026, which needs the option granted at least 2 years before the sale and the other relief conditions to be met. Even in the lower UK case, the UK tax of £8,460 is about $11,000, so a credit of that size leaves roughly $11,750 of US tax still to pay. The US figure stands because the IRS ignores Business Asset Disposal Relief altogether.

Common mistakes with EMI options and US tax

• Assuming a nil UK charge means nothing to report. The US exercise income is reportable even where PAYE was not operated, and the UK employer will usually not withhold US tax.
• Relying on the HMRC valuation for US purposes. The two valuations answer different questions.
• Treating a discounted EMI option as routine. A below-market exercise price needs a section 409A review before grant.
• Filing an 83(b) election on the option grant. It does nothing for an unexercised option, and a late election on exercise shares cannot be repaired.
• Forgetting the green card. A green card holder is taxed on worldwide income like a citizen while the card is held.

What to do before you exercise

1. Read the option agreement and plan rules for the exercise price, exercise window, any early-exercise or repurchase rights, and any change of control terms.
2. Ask the company for the grant-date valuation and any US 409A valuation, and compare them with the exercise price.
3. Work out the US value at the planned exercise date and the dollar tax due, and plan how to pay it if the shares cannot be sold.
4. If you will receive restricted shares, diarise the 30-day 83(b) deadline from the transfer date before you sign.
5. Model the UK Capital Gains Tax and the Form 1116 credit together, for both countries' tax years.

Our tax planning team and the guide for UK company owners cover related ground. If you hold options now, contact us before exercising.