US Personal Tax Services: Convertible Bonds in the UK

For a UK-resident American, a listed convertible bond is taxed under two different systems. The US generally treats conversion into the issuer's shares as a non-event, with your basis carried over. The UK taxes coupons as savings income, may apply the accrued income scheme, and usually treats conversion as a reorganisation within capital gains tax.

That short answer hides most of the work. A convertible is a debt instrument with an equity option built in, and the US and UK both look at the debt and the option separately at different points: at purchase, on each coupon date, on a sale between coupon dates, at conversion and at redemption. Our US Personal Tax Services team prepares both returns for Americans in Britain who hold these bonds. This guide explains how each system treats a listed convertible, where the two treatments split apart, and how to report a conversion or redemption on a Form 1040 and a UK Self Assessment return without paying tax twice or leaving out something that has to be reported.

This guide is about listed convertible bonds, meaning exchange-traded or broker-held convertible debt issued by established companies. Convertible loan notes in private start-ups raise different questions, such as early-stage valuation, the qualified small business stock rules and UK investment-relief interactions. They are outside the scope of this guide. We do not name any issuer, and every specific threshold or rate below should be checked against the current rules for the tax year concerned.

Why do convertible bonds cause problems on a US-UK return?

Most generalist pages on convertible bonds are written for one country. US articles explain that conversion is generally tax-free and that original issue discount is taxed as it accrues. UK articles explain qualifying corporate bonds and the accrued income scheme. Neither kind deals with the American taxpayer living in London who has to file both returns for the same instrument, in two currencies and over two tax years that do not line up.

For that reader, the problems tend to show up in a few places:

• Timing mismatches. The US can tax accrued original issue discount (OID) each year even when no cash arrives. The UK may tax nothing until a coupon is paid, a sale happens or a discount is realised. Foreign tax credits only line up if the income is matched carefully between the two returns.
• Different characterisation. A gain on selling the bond may be capital in both countries, but how the accrued interest inside the price is treated can differ. The accrued income scheme moves part of it into UK income. US rules generally treat purchased accrued interest as a return of capital against the first coupon.
• Currency. A bond in US dollars held by a UK resident creates sterling gains and losses for UK purposes. A bond in sterling or euros held by a US citizen can create separate foreign currency gain or loss for US purposes on the principal and on the interest.
• Information reporting. UK brokers do not issue Forms 1099. Statements are in sterling, and they show no US basis adjustments for OID, market discount or premium.
• Conversion mechanics. Modern convertibles often settle in cash, in shares or in a mix of the two at the issuer's choice. The tax result can depend on which one the issuer picks.

How the US taxes a convertible bond while you hold it

Coupon interest

Stated interest that is paid at least annually at a fixed rate is generally qualified stated interest. A cash-basis individual includes it as ordinary income when it is received. For a US citizen in the UK, it goes on Schedule B in US dollars. If it is paid in a foreign currency, you convert each payment at the spot rate on the date you receive it, or use an acceptable average rate where that is allowed. Interest from a foreign issuer is foreign-source passive category income for foreign tax credit purposes. Interest from a US issuer is US-source, which affects how much UK tax can be credited (see the double tax section below).

Original issue discount, where present

The conversion feature does not create OID by itself. OID arises where the bond was issued at more than a de minimis discount to its stated redemption price at maturity, or where some of the return is not qualified stated interest, as with a zero-coupon convertible or one that accretes to a redemption premium. In those cases the holder generally includes OID in income each year on a constant-yield basis, whether or not cash is received. Each amount included is added to your tax basis in the bond. That matters later: if the bond converts, the OID you have already been taxed on is carried into the basis of the shares rather than lost.

Contingent payment debt rules can turn a straightforward instrument into a complicated one. However, the US regulations generally exclude debt that is convertible into the issuer's own stock from those rules. If the bond converts into the stock of a different company, such as an exchangeable bond, or includes other contingencies, the analysis needs to be done again.

Market discount and acquisition premium

If you bought the bond in the secondary market below its adjusted issue price, you have market discount. Unless you elect to include it currently, accrued market discount is generally taxed as ordinary income when the bond is sold or redeemed. On conversion into the issuer's stock, however, accrued market discount generally carries over to the shares and becomes ordinary income when those shares are later sold.

Bond premium, and the part attributable to the conversion feature

Investors often miss this point. If you pay more than the bond's principal, and convertibles often trade above par because of the equity option, US rules generally prevent you from amortising the part of the premium that relates to the conversion feature. Only premium beyond the value of the option can be amortised as bond premium, and only if you have made the relevant election, which then applies to all your taxable bonds. In practice, most of the premium on a convertible trading well above par because of a strong share price stays in your basis. It is recovered on sale, or carried into the shares on conversion. It is not deducted year by year against coupons.

What happens for US tax purposes when the bond converts?

Conversion into the issuer's shares

Under long-standing US authority, converting a bond into the stock of the same issuer under the bond's own terms is generally not a realisation event. No gain or loss is recognised, even if the shares are worth much more than you paid for the bond. Your adjusted basis in the bond, including OID already included and adjusted for any amortised premium, generally becomes your basis in the shares. Your holding period in the bond generally carries over as well, which matters for long-term capital gain treatment when you sell the shares.

There are two common exceptions inside an otherwise tax-free conversion:

• Accrued but unpaid interest. If some of the shares (or cash) you receive is effectively paid for interest that has accrued and has not yet been included in income, that part is generally taxable as interest. Many indentures say that accrued interest is forfeited, or deemed paid by the shares, on conversion. The wording matters, and US practice on deemed-paid interest is not completely settled.
• Cash for fractional shares. Cash paid instead of a fractional share is generally treated as if you received the fraction and sold it, giving a small capital gain or loss.

Cash settlement and partial cash conversions

Many listed convertibles now give the issuer a choice when a holder converts: deliver shares, pay cash, or pay cash up to the principal and shares for any excess (often called "net share settlement"). The US result follows the form:

• All cash. This is generally a taxable sale or retirement of the bond. You recognise gain or loss equal to the cash received, minus any amount for accrued interest, less your adjusted basis. Accrued market discount becomes ordinary income.
• Cash plus shares. This is the area that most needs advice. If the bond counts as a "security" for reorganisation purposes, the exchange may be a recapitalisation. In that case, gain is generally recognised only up to the cash received, losses are not recognised, and basis is allocated between shares and cash under the reorganisation rules. Otherwise, the transaction may be split into a tax-free conversion of part of the bond and a taxable redemption of the rest. Each approach has support. The issuer's own tax disclosure (often in the offering memorandum, or in a later information statement) usually states its view, and that view should be reviewed before the return is filed.

Redemption, put and maturity

If the bond is redeemed for cash at maturity, at a holder put date or at an issuer call date, this is a taxable retirement. Gain or loss is capital, except for accrued market discount and any amount for unpaid interest. The sale goes on Form 8949 and Schedule D in US dollars. For non-dollar bonds, any foreign currency gain or loss on the principal is calculated separately and is generally ordinary.

How the UK taxes a convertible bond held by a UK resident

Interest as savings income

Coupons received by a UK-resident individual are savings income. They are taxed at the savings rates after the personal savings allowance and, where available, the starting rate for savings. Most high earners lose part or all of the personal savings allowance, so additional-rate taxpayers should usually expect the full additional rate on coupons. Coupons on overseas bonds are taxable when they arise, and any foreign withholding may be creditable.

Is a convertible bond a qualifying corporate bond?

This classification decides almost everything else on the UK side. A qualifying corporate bond (QCB) is exempt from capital gains tax: no chargeable gain and no allowable loss arises on disposal. Broadly, to be a QCB a security has to be a normal commercial loan expressed in sterling, with no right to conversion into shares or other securities and no right to redemption in a currency other than sterling. In consequence:

• A convertible bond with a real conversion right into shares is generally not a QCB, so it is a chargeable asset within capital gains tax.
• A bond in US dollars or another non-sterling currency is generally not a QCB either, even without a conversion feature.
• Some exchangeable or "synthetic" structures, and bonds where the conversion right has lapsed or is purely nominal, need checking case by case.

Many American investors find this surprising. A gain on a sterling corporate bond can be UK-exempt, while a gain on a convertible from the same issuer is taxable at UK capital gains tax rates. Losses work the same way: a loss on a non-QCB convertible is generally allowable for capital gains tax, which a loss on a QCB would not be.

The accrued income scheme on purchases and sales between coupon dates

If you buy or sell an interest-bearing security between coupon dates, the price includes interest that has accrued since the last coupon. The UK accrued income scheme taxes that accrued interest as income rather than leaving it in the capital gain or loss calculation:

• A seller is generally taxed on the interest accrued up to the settlement date (an "accrued income profit"). The same amount is excluded from the disposal proceeds for capital gains purposes.
• A buyer generally gets relief for the accrued interest paid for, set against the next coupon (an "accrued income loss").
• The scheme generally does not apply to an individual whose holdings of relevant securities have a total nominal value at or below a de minimis threshold (historically £5,000) in the relevant tax year or the previous one. A portfolio of several convertibles usually exceeds it.

The accrued income scheme does not line up with US practice. For US purposes, interest you paid for on purchase is generally a return of capital against the first coupon, and interest accrued up to a sale is generally included in income as interest. The economic result is similar, but the amounts are calculated in different currencies, on different settlement-date conventions and often fall in different tax years because of the April and December year-ends. Reconciling them is a core part of preparing these returns.

Conversion into shares for UK purposes

Where a non-QCB convertible is converted into shares of the issuer, UK law generally treats the conversion as a reorganisation of share capital. The shares received are generally treated as the same asset as the bond, with the bond's acquisition cost and acquisition date carrying across, and no disposal arises at that point. Cash received on conversion is a part disposal, unless it is small compared with the value of the holding. Where the cash is small (broadly, not more than 5% of the value, or £3,000 if greater), HMRC practice generally allows it to be deducted from base cost rather than taxed immediately.

If the bond is a QCB that converts into shares (which is unusual for a true convertible, but can happen with certain restructurings or loan-note exchanges), different rules apply. A gain is calculated at the time of the exchange and "frozen", to be charged when the new shares are later disposed of. That is a very different result from the US, and it needs to be identified before either return is prepared.

Redemption and sale for UK purposes

For a non-QCB convertible, redemption or sale is a capital gains tax disposal. The proceeds are reduced by any amount taxed under the accrued income scheme, and both cost and proceeds are converted to sterling at the rates on the relevant dates. A redemption premium may also need checking under the UK deeply discounted securities rules, which can tax a discount as income. Whether those rules apply to a particular convertible depends on its terms and on specific exclusions, so it should be confirmed before filing.

US vs UK treatment at a glance

Event	United States (Form 1040)	United Kingdom (Self Assessment)
Coupon received	Ordinary interest income (Schedule B), in USD at spot	Savings income at savings rates, in GBP
Original issue discount	Generally accrued annually on constant yield, even without cash; increases basis	No annual accrual for a typical non-QCB convertible; any discount may be taxed on disposal or redemption, subject to the deeply discounted securities rules
Premium paid above par	Premium attributable to the conversion feature is not amortisable; stays in basis	Part of capital gains tax base cost
Purchase or sale between coupon dates	Purchased accrued interest offsets first coupon; accrued interest on sale is interest income	Accrued income scheme: income adjustments, removed from capital gains tax computation (subject to de minimis)
Conversion into issuer shares	Generally no gain or loss; basis and holding period carry over	Generally a reorganisation: no disposal; cost and date carry over (non-QCB)
Cash for fractional shares	Small capital gain or loss	Usually small part disposal or base cost reduction
All-cash settlement or redemption	Taxable disposal: capital gain or loss, with market discount as ordinary income	Capital gains tax disposal of a chargeable asset (non-QCB)
Cash plus shares	Recapitalisation (gain recognised up to cash) or split conversion and redemption: fact-specific	Part disposal for the cash element, unless small
Currency movements	Separate foreign currency gain or loss on non-USD principal and interest, generally ordinary	Everything computed in GBP; FX is inside the gain

How do you avoid double tax on convertible bond income and gains?

The US-UK income tax treaty and the US foreign tax credit rules work together, but neither applies automatically, and convertibles create several mismatches:

• UK tax on coupons from a non-US issuer. The income is foreign-source for the US, so UK tax paid on it can generally be credited on Form 1116 in the passive category. In practice, UK rates on savings income for higher and additional-rate taxpayers usually exceed the US rate on the same interest, so excess credits are common.
• Coupons from a US issuer. US-source interest normally leaves no room under the foreign tax credit limitation. The treaty's re-sourcing and relief articles may let the US citizen credit UK tax in some cases, or the UK may give relief for any US tax actually withheld. The order of relief needs to be worked through on the specific facts.
• Timing gaps. US OID accrued in a year the UK taxes nothing, followed by a UK charge on redemption in a year the US taxes little, can leave foreign tax credits stranded. Carryback and carryforward rules help, but only if the returns are prepared with the whole life of the bond in view.
• Conversion followed by share sale. Both countries generally defer at conversion, so the large gain usually arises on the eventual sale of the shares. Because UK cost is in sterling and US basis is in dollars, the two gains can differ substantially. The UK capital gains tax is generally creditable against the US tax on the gain, but the net investment income tax raises separate questions that should be reviewed with an adviser.

How to report a conversion or redemption on both returns

On the US return

1. Build the US basis record. Start with the USD cost on the trade date, including commissions. Add OID included in each year and any market discount you elected to include currently. Subtract any bond premium amortised under an election (the conversion premium cannot be amortised). Your broker will not have done this.
2. Read the settlement notice. Note how many shares you received, any cash for fractional shares, any cash paid instead of shares and how the indenture treats accrued interest.
3. Pure share conversion. No Form 8949 entry is needed for the conversion itself, apart from cash for fractional shares. Carry the adjusted basis and original acquisition date into the new share lot, and note any carried-over market discount.
4. Cash or mixed settlement, or redemption. Report the disposal on Form 8949 and Schedule D. Report the interest element on Schedule B, and accrued market discount as ordinary income. For non-USD bonds, calculate the foreign currency gain or loss separately.
5. Foreign tax credit. Match UK tax on the same item, in the same category and as far as possible to the same period, on Form 1116.
6. Information returns. Bonds held at a UK broker count towards specified foreign financial assets. Check whether Form 8938 is required, and include the brokerage account on the FBAR if aggregate foreign account balances exceed the reporting threshold at any point in the year.

On the UK return

1. Classify the bond. Confirm it is not a QCB (conversion right, currency) and check whether the deeply discounted securities rules could apply.
2. Coupons. Report them as interest. For non-UK issuers, they go on the foreign pages, with any foreign tax deducted.
3. Accrued income scheme. Where the de minimis threshold is exceeded, include accrued income profits as savings income and use accrued income losses against the relevant coupon. Remove the same amounts from the capital gains tax calculation.
4. Conversion. Record the new shares with the bond's sterling cost and original acquisition date. Deal with any cash received as a part disposal or a base cost reduction.
5. Redemption or cash settlement. Report it on the capital gains pages with sterling proceeds and cost. Remember that the UK share-matching rules (same-day and 30-day) can apply to shares acquired on conversion if you also trade the same shares.

Problems we find when we review returns

• The UK broker's sterling gain is copied onto Form 8949 without converting cost and proceeds at the correct USD rates on their own dates.
• OID is not accrued on the US return for years, which understates income and leaves the share basis too low after conversion.
• The whole premium over par on a convertible is amortised, including the part attributable to the conversion feature, which is not permitted.
• A convertible is treated as UK-exempt because the client's other corporate bonds are QCBs.
• A net-share-settled conversion is reported as entirely tax-free on the US return, with the cash element ignored.
• The FBAR and Form 8938 are left out because "they're just bonds at my UK broker".

If any of these apply to earlier years, it can usually be put right. Missed income, information returns and FBARs can often be dealt with through amended returns or, where the failures were non-wilful, through the IRS streamlined filing procedures. The FBAR exposure can be estimated with our FBAR penalty calculator.

What records should UK-resident Americans keep for convertible bonds?

• The offering memorandum or prospectus summary of the conversion terms, settlement options and the issuer's stated tax position.
• Trade confirmations showing clean price, accrued interest and settlement date for every purchase and sale.
• Annual OID and yield figures for US reporting, where relevant.
• Conversion or redemption notices with shares, cash and fractional cash itemised.
• Sterling and dollar exchange rates for each relevant date.
• Annual broker statements and year-end values for FBAR and Form 8938.

For the underlying IRS rules on OID, market discount and bond premium, IRS Publication 550 is the main reference. HMRC's Capital Gains and Savings and Investment manuals cover QCBs, reorganisations and the accrued income scheme.

How Jungle Tax prepares these returns

Jungle Tax prepares US and UK returns together for Americans in Britain, so the same convertible is treated consistently on both. We keep a dual-currency basis record for each bond and reconcile accrued income scheme entries against US accrued interest. We review the issuer's settlement terms before deciding how a conversion is reported, and we match foreign tax credits across the two tax years. Clients with wider portfolios often use the same engagement for their US expat returns and UK Self Assessment, and our high-net-worth practice deals with larger multi-broker holdings.

If you hold listed convertibles, have had a conversion or cash settlement this year, or suspect earlier returns did not reflect OID, premium or the accrued income scheme correctly, contact our cross-border team for a confidential consultation. We will review your positions, identify anything that needs correcting and prepare US and UK filings that agree with each other.