I filed my 83(b) on time but never signed a section 431 election. Is there anything I can do now?

There is no general mechanism to make a section 431 election out of time, and the treaty will not deem one to have been made. Your realistic options involve managing the UK charge as it arises and examining whether any foreign tax credit or re-sourcing analysis can reduce the mismatch on the eventual disposal. This is salvage work rather than a fix, and it should begin before the next vesting date rather than after it, because the arithmetic worsens with each tranche that lifts.

Does the section 431 election cost me anything if my shares are worth very little?

For a founder subscribing at incorporation at unrestricted market value, the election typically crystallises no additional charge, because there is no spread between what you paid and the unrestricted value. That is why it is so widely described as a free option. The calculus changes materially for an executive receiving valuable restricted stock mid-cycle, where electing means paying income tax up front on the full unrestricted value with no shares available to sell to fund it.

My shares were granted by a US parent, not the UK company I work for. Do the UK rules still apply?

Very likely yes. The UK employment-related securities rules look at whether the securities were acquired by reason of employment, not at which entity in the group issued them. A grant from a US parent over its own stock to a UK-based employee is generally caught, and the section 431 election is made with the UK employing entity. Group grants are one of the most common contexts in which the election is overlooked entirely, precisely because the US parent's equity administrator has no UK process.

How is the 14-day deadline actually measured?

It runs from the acquisition of the employment-related security under UK law, which may not be the date on your share certificate or the date your US counsel treats as the transfer date for section 83 purposes. Where a board resolves to allot and documentation follows later, the clock may already be running. Establishing the acquisition date with certainty before the grant is completed is the single most valuable step in the whole process, and HMRC's Employment Related Securities Manual on GOV.UK is the reference point.

If I pay UK income tax on vesting, why can't I just claim a foreign tax credit later when I sell?

Because foreign tax credit relief broadly requires the same income to be taxed by both countries in a way the crediting rules recognise, and your 83(b) election deliberately moved all US recognition to the grant year. The UK charge arises years earlier, as employment income, while your US gain arises on disposal, as capital. The credit does not reach backwards across years, and income and capital fall into different limitation categories, so there is generally nothing to offset.

Do the elections interact with my other US filings for the UK company?

Not directly, but they sit inside the same compliance perimeter. Owning a UK company can trigger Form 5471 and controlled foreign corporation analysis, sale proceeds in UK accounts can trigger FinCEN Form 114 and Form 8938 once aggregate balances exceed the statutory thresholds, and UK funds may raise Section 1291 passive foreign investment company issues. All of these share the elections' defining feature: the exposure attaches to the failure to file, regardless of how much tax is actually owed. Current thresholds should be confirmed on IRS.gov.

83(b) and Section 431: The Double Election Trap

If you are a US person receiving restricted shares from a UK employer or your own UK company, filing a section 83(b) election with the IRS solves only half your problem. You must also file a section 431 election with your employer within 14 days of acquiring the shares, or HMRC will tax the same equity a second time on its value at vesting — in a tax year where your US return shows no corresponding income and therefore generates no foreign tax credit to shelter it. The two elections look superficially similar and are often described interchangeably by advisers who work on one side of the Atlantic only. They are not the same instrument, they run on different clocks, they are filed with different parties, and the treaty will not repair a missed deadline. This is one of the few areas of cross-border planning where a purely administrative failure, measured in days, converts a tax-efficient founding stake into a permanently double-taxed one.

What does a section 83(b) election actually do under US law?

Section 83 of the Internal Revenue Code governs property transferred in connection with the performance of services. The default rule is that you are not taxed when you receive shares subject to a substantial risk of forfeiture — typically a vesting schedule tied to continued service or founder reverse-vesting. Instead, you are taxed as each tranche vests, on the excess of the then-current fair market value over what you paid. For a company whose value is climbing, that default is punishing: you recognise ordinary compensation income on appreciation you have created, at the moment you least want a tax bill, and your capital gains holding period restarts with each tranche.

The section 83(b) election reverses this. By electing, you choose to be taxed immediately at grant on the spread between the value of the shares and the price paid. For a founder subscribing at nominal value at incorporation, that spread is usually negligible or nil, so the election costs almost nothing in tax and buys everything: all subsequent appreciation is capital, not compensation, and the holding period begins at grant. It is, for early-stage equity, close to a free option — which is precisely why sophisticated US founders file it reflexively.

The election must be filed with the IRS within a short, statutorily fixed window that begins on the date of transfer. There is no reasonable-cause relief for a late filing in the ordinary sense, and the window is measured from transfer, not from when your lawyer got around to issuing the share certificate. The current mechanics and filing address are set out on IRS.gov, and you should confirm them at the time of grant rather than rely on a template your US counsel drafted for a previous round.

Why does the UK need a separate election at all?

The UK reaches the same problem from a completely different direction. Chapter 2 of Part 7 of the Income Tax (Earnings and Pensions) Act 2003 deals with restricted securities — shares acquired by reason of employment that carry restrictions on transfer, forfeiture provisions, or other conditions that depress their market value. Where an employee acquires restricted securities, the UK taxes an initial amount at acquisition based on the restricted value, and then imposes a further income tax charge on the proportionate uplift when the restrictions lift or the shares are sold. The theory is that the employer conferred a benefit by giving you something whose value was artificially suppressed and would inevitably rise as the shackles came off.

The section 431 election disapplies that machinery. By electing, you and your employer jointly agree to treat the shares as if the restrictions did not exist — you pay income tax up front on the unrestricted market value, and everything thereafter falls into the capital gains regime. Where you have paid full unrestricted market value for the shares, as a founder subscribing at incorporation typically has, the election crystallises nothing and costs nothing. It simply closes the door on a future income tax charge.

Note the crucial structural difference: the section 431 election is not filed with HMRC. It is a joint election between employee and employer, executed and retained, and produced only if HMRC asks. This means there is no filing receipt, no postmark, and no third-party record — which is exactly why so many are never actually executed. Everyone assumes someone else has it. GOV.UK publishes the standard forms and explains the mechanics; HMRC's Employment Related Securities Manual is the authoritative source on how the charge operates.

How exactly do the two deadlines fail to line up?

The section 431 election must be made within 14 days of the acquisition of the securities. The section 83(b) election runs on its own, longer statutory clock from the date of transfer. The dates from which each clock runs are also determined by different bodies of law — the US concept of transfer and the UK concept of acquisition of an employment-related security are not guaranteed to fall on the same calendar day, particularly where shares are issued subject to conditions precedent, where a share certificate lags the board resolution, or where a US parent grants over a UK subsidiary's employees.

The practical consequence is brutal in its simplicity: by the time a US founder's American counsel has diarised the 83(b) deadline and prepared the filing, the UK 14-day window may already have closed. The 431 election has the tighter deadline and the lower visibility. It is the one that gets missed, and it is missed by exactly the people who are most diligent about the 83(b) — because they believe, understandably, that having handled the election, they have handled the elections.

What does the mismatch cost in practice?

Consider a US citizen who founds a UK company, subscribes for restricted shares at nominal value with four-year reverse vesting, and files a timely 83(b). Her US position is clean: she recognised a trivial amount of ordinary income at grant, and every pound of subsequent appreciation is capital gain, taxable only on disposal. Her UK position, absent a section 431 election, is the opposite. Each time a tranche of her shares ceases to be forfeitable, HMRC imposes an income tax charge on the proportion of the unrestricted value attributable to the lifted restriction. That charge is employment income. It may carry National Insurance. If the shares are readily convertible assets, it may be pushed through PAYE, leaving her employer obliged to account for tax on shares she cannot sell to fund it.

Now find the credit. Foreign tax credit relief under the US-UK double tax treaty and the domestic credit provisions requires, broadly, that the same income be taxed by both jurisdictions in a way the crediting rules recognise. But she has no US income in the vesting years — her 83(b) election deliberately moved all of it to the grant year. There is nothing on her Form 1040 for the UK tax to credit against. Conversely, when she eventually sells and reports a US capital gain, the UK charge arose years earlier, as income, on a different measure, and against a different category of income for limitation purposes. The credit does not reach backwards, and it does not cross freely between income baskets and years.

The result is not merely a timing inconvenience. It is genuine, permanent double taxation on the same economic appreciation — UK income tax on the vesting uplift, US capital gains tax on the eventual sale proceeds, and no mechanism to reconcile the two. The 83(b) election, filed correctly and in good faith, has actively destroyed the relief that would otherwise have been available.

Which mistakes recur most often in cross-border grants?

Assuming the 83(b) covers both jurisdictions. The elections address different statutory charges under different codes. Filing one does nothing for the other, and no adviser's assurance that 'the election has been made' should be accepted without asking which election, filed with whom, and on what date.
Missing the 14-day window because nobody identified the acquisition date. The clock starts on acquisition of the employment-related security, which may precede the paperwork. Where a board resolves to allot and the certificate follows weeks later, the window may already be running.
Believing there is a late-filing remedy. There is no general HMRC discretion to accept a section 431 election out of time, and no treaty article that retroactively deems one to have been made. The deadline is the deadline.
Treating founder shares as outside the employment-related securities rules. The UK definition is broad and the statutory presumption where shares are acquired by an employee or director is difficult to displace. Founders who consider themselves owners rather than employees are frequently caught anyway.
Executing the election but never retaining it. Because nothing is filed with HMRC, the only evidence is the document itself. Elections lost in a defunct law firm's files, or never counter-signed by the employer, are functionally elections that were never made.
Overlooking the election on secondary events. Later share issues, growth shares, sweet equity in a private equity structure, and shares acquired on an exchange in a reorganisation can each restart the analysis and each require their own election.

Does the treaty rescue a late or missing election?

No, and this is the point most often misunderstood by clients who have absorbed the general reassurance that the US-UK double tax treaty prevents double taxation. The treaty allocates taxing rights and provides relief mechanisms between the two states. It does not harmonise the timing of domestic tax charges, and it does not deem a domestic election to have been made where the domestic deadline was missed. Article 24 relief and the associated domestic credit rules operate on income that both countries tax; they are not a general equitable remedy for a taxpayer whose two returns simply do not overlap in time.

There are situations in which careful re-sourcing analysis, the treaty's relief provisions, or the timing rules for foreign tax credits can mitigate part of the exposure — but these are salvage operations, expensive, uncertain, and dependent on facts that vary case by case. They are not a substitute for a signed document that costs nothing and takes minutes. It is worth saying plainly: the cheapest tax planning available to a US founder in Britain is a piece of paper executed within 14 days, and the most expensive advice they will ever buy is the analysis required after they did not execute it.

How should the election interact with the rest of a founder's US filings?

The double election sits inside a wider compliance perimeter that US founders in the UK cannot ignore. Ownership of a UK company brings potential Form 5471 obligations, with all the attendant subpart F, GILTI and section 962 questions that follow from controlled foreign corporation status. UK bank and brokerage accounts holding sale proceeds trigger FinCEN Form 114 and potentially Form 8938 once aggregate balances cross the statutory thresholds, which are published and periodically revised — check IRS.gov rather than assume. UK funds held alongside the equity may be passive foreign investment companies, dragging Section 1291 into the picture. UK pension arrangements and certain trust structures raise Form 3520 and Form 3520-A questions.

Form 5471, where ownership or control of the UK company crosses the statutory tests. Controlled foreign corporation status pulls subpart F, GILTI and the section 962 election into an annual analysis that has nothing to do with whether the company has ever paid a dividend.
FinCEN Form 114 and, once the separate FATCA thresholds are met, Form 8938. Both are triggered by aggregate account balances rather than by income, and the applicable thresholds are published on IRS.gov rather than fixed in perpetuity.
Section 1291 and the PFIC regime, where sale proceeds are parked in UK funds, OEICs or investment trusts. The default regime is punitive, and the QEF election that would soften it depends on information most UK managers do not produce.
Forms 3520 and 3520-A, where a UK pension arrangement or family trust structure sits alongside the equity. The reporting analysis turns on the specific documents, and relief for certain tax-favoured arrangements is conditional rather than automatic.
The UK side of the same events, where HMRC's employment-related securities reporting obligations fall on the employer and run to their own annual deadline. GOV.UK sets out the current filing mechanics, which are separate from anything filed with the IRS.
Evidence retention across all of it, since the elections, the board minutes and the valuation support are the documents that make every position above defensible years later, when the company is being sold and a buyer's counsel is reading the file.

None of this is directly caused by the elections, but all of it shares a characteristic with them: these are regimes where the penalty attaches to the failure to file, not to the amount of tax owed. A founder who has built a genuinely tax-efficient structure can still be dismantled by paperwork. The elections are simply the earliest and most consequential example.

What should you do before your next grant?

Treat every acquisition of UK shares by a US person as a dual-election event by default, and rebut that presumption deliberately rather than by omission. Before any board approves an allotment, establish the exact acquisition date, diarise the 14-day UK window and the US window separately, and confirm that a single named person — not 'the lawyers' — is responsible for each. Ensure the section 431 election is counter-signed by the employer and stored somewhere that will survive a change of counsel, a company sale, or a founder departure.

Equally, do not file an 83(b) reflexively without asking what it does to your UK position. There are fact patterns — particularly where a founder expects to leave the UK, where the shares are unlikely to appreciate, or where a UK charge is unavoidable for other reasons — in which the interaction merits genuine thought rather than a template. The election is close to free for a founder at incorporation; it is emphatically not free for an executive receiving materially valuable restricted stock mid-cycle, where the up-front charge may be real in both countries.

The rules described here are structural and stable, but rates, thresholds and filing mechanics change every tax year. Current figures and forms should always be taken from IRS.gov and GOV.UK directly. And because the outcome turns entirely on your own dates, your residence position, your domicile history, and the precise terms of your share agreement, this article is not a substitute for advice on your facts. If you are about to receive restricted equity from a UK employer, or you suspect an election was missed on a grant already made, take advice before the next vesting date rather than after it — the window for cheap solutions closes quickly, and the window for any solution at all closes not long after.