US Personal Tax Services: Index-Linked Gilts and TIPS

A UK-resident American who holds index-linked gilts or US TIPS directly is taxed on the same bond in two incompatible ways. The United States taxes the inflation uplift on principal each year as phantom income, measured in dollars. The UK taxes only the coupon on a gilt and treats TIPS quite differently. The two returns rarely reconcile.

That gap is where US personal tax services earn their fee for an internationally mobile investor. Inflation-linked government bonds are bought for their simplicity: sovereign credit, a real return, and in the UK a famously light tax charge. On a Form 1040 they are among the most technical holdings in a private portfolio. At Jungle Tax we prepare both returns for Americans living in Britain, and index-linked stock is one of the positions we most often find reported correctly to HMRC and incorrectly, or not at all, to the IRS. This guide sets out how each system treats the two instruments, why the foreign tax credit does not close the gap, and what each return has to show. It does not revisit the mechanics of conventional gilts or Treasury bills, which we cover separately in our guides library.

How do index-linked gilts and TIPS actually work?

Both instruments protect the holder against inflation by adjusting the principal, and therefore every coupon calculated on it, by reference to a price index.

• Index-linked gilts are sterling obligations of the UK government. Principal and coupons are scaled by the movement in the UK Retail Prices Index, with a three-month indexation lag on all modern issues and an eight-month lag on a small number of older ones. Coupons are paid semi-annually. There is no floor: in sustained deflation the redemption payment can fall below the original nominal amount.
• TIPS are dollar obligations of the US Treasury. Principal is adjusted by a daily index ratio derived from the US consumer price index for all urban consumers. A fixed real coupon is paid semi-annually on the adjusted principal. At maturity the holder receives the greater of adjusted principal and original par, so there is a deflation floor on principal, though not on coupons.

Economically the two are close cousins. For tax purposes they fall under four different regimes: two in the United States and two in the UK.

How does the IRS tax TIPS held by an American living in the UK?

TIPS are governed by the US inflation-indexed debt instrument regulations. For a bond issued at or near par with a fixed real coupon, which describes TIPS bought at auction, the rules apply what is called the coupon bond method.

The coupon and the uplift are taxed separately, and both annually

• The coupon is qualified stated interest, taxed under the holder's ordinary method of accounting. For a cash-basis individual that means when it is received.
• The inflation adjustment is original issue discount. For each year, it is the inflation-adjusted principal at the end of the period, plus any principal repaid, less the inflation-adjusted principal at the start. A positive figure is ordinary interest income for that year, although nothing has been paid. This is the phantom income.
• Basis rises by every dollar of adjustment taxed, so the uplift is not taxed a second time on sale or redemption.

Interest on US Treasury obligations is exempt from state and local income tax, which matters to a UK resident only if a US state still asserts residence. Federal tax applies in full. The IRS explains the computation in Publication 1212, its guide to original issue discount instruments.

What happens when the index falls?

A negative adjustment is a deflation adjustment, and the regulations prescribe a strict order for using it:

1. It first reduces the interest otherwise includible on that bond for the year, including the cash coupon.
2. Any excess is an ordinary loss, but only up to the total interest included on the bond in earlier years, less any such losses already taken.
3. Anything still unused carries forward to reduce interest on the same bond in later years.

If the par floor operates at maturity, the additional payment that restores the holder to par is ignored until it is made and is then treated as interest. Deflation adjustments are tracked bond by bond; they cannot be pooled across a ladder of different issues.

Bought in the secondary market?

Most private holders buy seasoned issues rather than subscribing at auction, and the purchase price will rarely equal the adjusted principal. A purchase above it produces bond premium, which may be amortised by election against the coupon, with any excess reducing the positive inflation adjustment. A purchase below it produces market discount, which converts what would otherwise be capital gain into ordinary income on disposal unless the holder elects to accrue it currently. Neither item exists in UK tax, and neither appears on any UK statement.

No Form 1099-OID from a UK custodian

A US broker reports the annual adjustment on Form 1099-OID. A UK custodian issues no US information returns at all. Its statements show the cash coupon and, usually, a dollar market value. The adjustment has to be reconstructed from the published index ratios for each issue at each year end and at each purchase and sale settlement date. The obligation to report it is unaffected by the absence of a form.

Are index-linked gilts taxed like TIPS on a US return?

This is the point on which most published commentary is wrong, or at least incomplete. It is routinely said that the uplift on an index-linked gilt is original issue discount in exactly the same way as on TIPS. The outcome is similar in kind, but the governing rules are different, and the differences change the numbers.

The inflation-indexed debt regulations define their own scope narrowly. An instrument qualifies only if it is issued for US dollars with all payments denominated in US dollars, and only if it is linked to a qualified inflation index, meaning a general price or wage index published at least monthly by an agency of the US government. A sterling bond indexed to the UK Retail Prices Index fails both conditions.

An index-linked gilt is instead a debt instrument denominated in a non-functional currency with a contingency other than currency. In our reading it therefore falls to be analysed under the regulations for foreign currency contingent payment debt instruments, which apply what is called the noncontingent bond method in the currency of the bond and then translate the result. In outline:

1. Comparable yield. Determine, in sterling, the yield at which the issuer would have issued a fixed-rate bond on similar terms. For a gilt the natural reference is the yield on a conventional gilt of comparable maturity.
2. Projected payment schedule. Build a schedule of sterling coupons and a projected redemption amount that together produce that yield.
3. Annual accrual. Accrue interest each year at the comparable yield on the adjusted issue price, in sterling, regardless of what inflation actually did.
4. Adjustments. Where actual payments differ from the projected ones, a positive adjustment is additional interest and a negative adjustment reduces interest, with an ordering rule for any excess.
5. Translation. Translate the accrued interest into dollars at the average exchange rate for the accrual period, or at the spot rate by election. A net positive adjustment is translated at the spot rate on the last day of the tax year.

Three consequences follow that do not arise with TIPS.

• The annual inclusion is not simply the year's indexation. It is an accrual at a market yield fixed at the outset, trued up as payments are made. In a low-inflation year the holder may be taxed on more than the indexation actually credited.
• Gain on sale is generally ordinary. Under the contingent payment rules, gain on disposal is treated as interest income, not capital gain. A loss is ordinary only to the extent of net income previously included, and capital beyond that. An investor expecting long-term capital gain rates on a gilt sold at a profit will not get them.
• Secondary-market buyers carry an extra reconciliation. Where the purchase price differs from the adjusted issue price, the difference has to be allocated across the remaining accruals and projected payments.

No issuer statement supplies a comparable yield or projected payment schedule for a gilt, so the holder's preparer must construct and document one, and apply it consistently for the life of the holding. Some practitioners instead apply the TIPS method by analogy. Whichever basis is adopted, it should be a deliberate, recorded position, not an accident of software.

The section 988 currency layer

Sterling is a foreign currency for a US taxpayer wherever they live. Exchange gain or loss on a sterling debt instrument is computed separately under section 988 and is ordinary, not capital:

• on principal, by comparing the sterling amount at the spot rate on disposal with the same amount at the spot rate on acquisition;
• on accrued interest, by comparing the spot rate when it is paid with the rate at which it was accrued into income.

Because the uplift is accrued into dollar income year by year at that year's rates, each layer of accrued indexation carries its own exchange history. A gilt held for a decade has ten of them. On redemption the amount received must be separated into principal and each year's accrued interest before any currency result can be computed. A single average rate applied to a sterling net figure will always be wrong.

TIPS involve no section 988 computation at all on the US return: the dollar is the functional currency. The currency exposure on TIPS arises on the UK return instead, as explained below.

How does HMRC tax index-linked gilts?

The UK position for an individual is short, and it is the reason these bonds are so widely held by higher-rate taxpayers.

• Coupons are savings income, paid gross without deduction of tax and charged at the holder's marginal rate, currently 20%, 40% or 45%. The personal savings allowance is £1,000 for basic-rate and £500 for higher-rate taxpayers, and nil at the additional rate. The savings rates are legislated to rise by two percentage points from April 2027.
• The indexation uplift on principal is not interest and is not charged to income tax.
• Gains on disposal or redemption, including the whole of the uplift, are not chargeable gains under the exemption for gilt-edged securities. Losses are correspondingly not allowable.
• Gilts other than strips are excluded from the deeply discounted securities regime, so the uplift is not recharacterised as income by that route either.
• The accrued income scheme applies to transfers between coupon dates where nominal holdings exceed £5,000, reallocating the accrued coupon between seller and buyer. HMRC's helpsheet HS343 sets out the computation. On index-linked stock the accrued amount is itself inflation-adjusted, so the figure must come from the contract note.

The result is that the dominant part of the return on an index-linked gilt, the uplift, is never taxed in the UK. For an American that is precisely the part the United States taxes every year.

How are TIPS treated on a UK tax return?

TIPS are frequently assumed to be the American equivalent of an index-linked gilt and therefore taxed in the same benign way. They are not. The capital gains exemption and the carve-out from the discount rules both depend on the security being a UK gilt-edged security. A US Treasury obligation is not one.

• Coupons are foreign savings income, reported on the foreign pages of the self-assessment return in sterling at the rate on the date of receipt.
• The uplift and any gain have to be tested under the deeply discounted securities rules. A security is deeply discounted where the amount payable on redemption will or may exceed the issue price by more than 0.5% for each year of its term, capped at 15%. HMRC's Savings and Investment Manual at SAIM3020 gives an example of an index-linked security that meets the test because the linkage may produce an increase above that margin. The carve-out for indexed securities is confined to those linked to the value of chargeable assets, which a general price index is not. On that footing TIPS will ordinarily be deeply discounted securities, though the analysis should be confirmed issue by issue.
• If the regime applies, the whole profit on sale or redemption is charged to income tax as savings income in the year of disposal, not to capital gains tax. No annual exempt amount is available, and for individuals a loss is generally not relievable.
• Sterling measurement. The profit is the sterling value of the proceeds less the sterling value of the cost, each at its own date. A weaker pound between purchase and sale therefore increases the UK income charge, even though the US return, in dollars, sees no currency result at all.
• Accrued income. A deeply discounted security sits outside the accrued income scheme; the disposal charge does that work instead.

Individuals in their first four years of UK residence after a long period abroad may be able to claim relief for foreign income under the regime that replaced the remittance basis from April 2025. Where that relief covers TIPS income, no UK tax arises on it and the US charge stands entirely unrelieved.

US versus UK treatment at a glance

Item	US return (IRS)	UK return (HMRC)
Index-linked gilt: coupon	Ordinary interest, translated to dollars	Savings income at marginal rate, paid gross
Index-linked gilt: uplift	Accrued annually as ordinary interest under the foreign currency contingent payment debt rules	Not taxed as income; outside capital gains tax
Index-linked gilt: gain on sale	Generally ordinary, plus separate ordinary section 988 currency gain or loss	Exempt; losses not allowable
TIPS: coupon	Ordinary interest when received	Foreign savings income, in sterling
TIPS: uplift	Original issue discount each year; basis increased	No annual charge; taxed as income on sale or redemption if a deeply discounted security
TIPS: deflation	Reduces interest, then limited ordinary loss, then carried forward	No annual relief; reflected only in the eventual profit
Currency	Dollar is functional; sterling legs translated individually	Sterling is functional; dollar legs translated individually
Tax year	Calendar year	6 April to 5 April
Information returns	None from a UK custodian	Consolidated tax certificate showing cash coupons only

Why does the foreign tax credit not fix the mismatch?

The US–UK treaty gives the country of residence the primary right to tax interest, and the UK does not withhold on gilt coupons. The United States nonetheless taxes its citizens under the treaty's saving clause, and relief depends on a foreign tax credit claimed on Form 1116. A credit requires foreign tax actually paid on income in the same category. Inflation-linked bonds break that link in three ways.

Index-linked gilts: a permanent difference

The UK taxes the coupon and nothing else. Modern index-linked gilts often carry very low real coupons, so the UK tax is small. The US taxes coupon and uplift. The only relief for the US tax on the uplift is whatever UK tax on the coupon exceeds the US tax on that same coupon, within the passive category. For a holder whose portfolio generates other highly taxed UK passive income, excess credits from elsewhere in the basket may absorb some of the charge. For a holder whose principal passive asset is the gilt itself, most of the US tax on the uplift is a real cost.

TIPS: a timing difference that may never unwind

Interest on a US Treasury obligation is US-source. Where the UK taxes a resident US citizen on it, the treaty allows the income to be treated as foreign-source to the extent needed for the US to credit the UK tax, reported in a separate category on Form 1116. That works reasonably well for the coupon, taxed in both countries in broadly the same period.

The uplift is another matter. The US taxes it each year as it accrues. The UK taxes it, if at all, in the year of sale or redemption, as part of a single sterling profit. The UK tax therefore arrives in a year when the US return shows little or no corresponding income, because US basis has already been stepped up. Unused foreign tax credits can be carried back one year and forward ten. On a long-dated holding, the UK tax can fall outside the reach of the years in which the US tax was paid.

Two further frictions

• Net investment income tax. The 3.8% charge on investment income above the statutory thresholds applies to interest and original issue discount, and under the Code is not reduced by foreign tax credits.
• Tax years. UK tax for a year ending 5 April has to be allocated to US calendar years. Whether credits are claimed on a paid or accrued basis is an election with lasting consequences.

A worked illustration

The figures below are simplified and illustrative only.

Index-linked gilt. An American in London holds £2,000,000 of adjusted principal in a gilt with a 0.125% real coupon. The index rises 4% over the year, adding £80,000 to principal. The UK taxes a coupon of roughly £2,500 and ignores the £80,000. The United States brings in the coupon together with an annual accrual of the same order as the uplift, translated into dollars, at ordinary rates. The UK tax available as a credit is a little over £1,000. Almost all of the US tax on the accrual is unrelieved, and it is paid from other resources because the bond has distributed almost nothing.

TIPS. The same individual holds $2,000,000 of TIPS with a 2% real coupon through a UK custodian. US inflation of 3% produces a $60,000 adjustment and coupons of a little over $40,000. The US taxes roughly $100,000 for the year. The UK taxes only the coupon, in sterling. Seven years later the bond is redeemed. The UK then charges the entire sterling profit to income tax in one year at up to the additional rate, including any gain attributable solely to a fall in sterling. The US return for that year shows no gain, because basis already includes every adjustment. The UK tax generates a credit with nothing to absorb it.

What must the two returns show?

On the US return

• Schedule B: coupons received and the annual accrual on each holding, with accrued interest and premium adjustments shown separately.
• Form 8949 and Schedule D, or ordinary income where the contingent payment rules recharacterise gain, for each disposal, with basis reflecting prior inclusions.
• Section 988 results on sterling instruments, as ordinary income or loss.
• Form 1116 by category, including the separate category for income re-sourced under the treaty where TIPS interest bears UK tax.
• Form 8960 for the net investment income tax.
• Form 8938 and the FBAR for UK custody accounts. Our FBAR penalty calculator indicates the exposure where these were missed.

On the UK return

• Gilt coupons as interest from UK securities, with accrued income scheme profits and losses on the additional information pages.
• TIPS coupons as foreign interest on the foreign pages, in sterling.
• Profit on disposal or redemption of TIPS as income in the year it arises, with the sterling computation retained.
• No entry for gilt disposals on the capital gains pages, but working papers kept to support the exemption.

The records that make both possible

Contract notes for every purchase and sale; the index ratio or reference index for each settlement date and each 31 December; clean and dirty prices; spot exchange rates for each leg from a consistent source; and, for gilts, the comparable yield and projected payment schedule adopted at acquisition. Our US–UK tax accountants build this as a ledger per security, from which both returns are then drawn.

What if earlier years were prepared from UK figures?

This is the common case. A UK return prepared correctly shows a modest coupon and nothing else. A US return prepared from that return, or from a consolidated tax certificate, omits the uplift entirely, year after year. On a seven-figure holding through a period of high inflation the understatement is substantial.

Where the omission was non-willful, the IRS Streamlined Filing Compliance Procedures will usually be the appropriate route. A taxpayer who meets the non-residency test files three years of amended or delinquent returns and six years of FBARs with a certification of non-willful conduct, and no offshore penalty applies under the foreign offshore procedure. Tax and interest remain due. The reconstruction is the substantive work: accruals must be rebuilt from acquisition, not merely for the three years filed, because basis and deflation carryforwards depend on the full history. Our IRS streamlined filing team prepares the computations and the supporting narrative together.

The reverse error is rarer but real: a UK return that treats a TIPS redemption as an exempt or capital item. That is corrected through an amended self-assessment return or a disclosure to HMRC, depending on the years involved.

Errors we see most often

• Reporting only the cash coupon on Schedule B because no Form 1099-OID was received.
• Treating the UK gilt exemption as if it applied on the US return.
• Applying the TIPS method to a gilt by default, without recognising that a position has been taken.
• Reporting gain on an index-linked gilt as long-term capital gain.
• Omitting the section 988 computation, or computing it on the net sterling figure.
• Failing to increase US basis for adjustments already taxed, so the uplift is taxed twice.
• Assuming TIPS share the gilt exemption on the UK return.
• Claiming a foreign tax credit for UK tax that was never charged on the income in question.
• Losing a deflation carryforward because it was not tracked bond by bond.

Have the position reviewed before the next coupon date

Inflation-linked government bonds are sound holdings and there is nothing irregular in owning them. For a US citizen or green card holder resident in the UK, however, they require two separate computations, in two currencies, over two tax years, with a credit position that has to be worked out and not assumed. If your returns have been prepared from UK paperwork alone, the US side is very likely incomplete. Please contact our cross-border team for a confidential consultation. We will review the holdings, rebuild the accruals, quantify any exposure across open years and prepare both returns on a consistent, documented basis.