Index-Linked Gilts Explained: How UK Inflation-Protected Government Bonds Work — June 2026 Update

Index-linked gilts adjust both coupon payments and principal repayment in line with the Retail Prices Index (RPI). That single design choice separates them from every other fixed-income instrument available to UK investors.

Take the 0⅛% Index-linked Treasury Gilt 2036 (TG36). The 0.125% coupon looks absurd next to a conventional 10-year gilt yielding 4.91%. But that coupon is a real yield — it sits on top of whatever RPI accrues between issue and payment. The 2036 linker's clean price today on 15 June 2026 is £85.14 but its dirty price is £135.18 — that roughly £50 gap is the cumulative inflation uplift on principal since the gilt was issued in 2013. You pay the dirty price; you get the inflation-uplifted principal back at maturity.

The indexation uses an 8-month lag for gilts issued before 2005 and a 3-month lag for newer issues. Payments don't respond instantly to inflation spikes — and they don't reverse instantly when peace breaks out either. The Iran-driven energy shock that pushed petrol to 156.8 pence per litre and diesel to 190.0 pence in April 2026 is still feeding through the 3-month pipeline. Linker holders will see those fuel-driven RPI uplifts land in their coupon payments through the summer. The peace deal's disinflationary impulse won't reach gilt payments until autumn at the earliest.

Linkers index to RPI — not CPI or CPIH. The latest ONS bulletin (released 20 May, next print 17 June) put CPI at 2.8% and CPIH at 3.0% for April, both down sharply from March thanks largely to the Ofgem energy price cap reduction that cut electricity prices by 8.4%. RPI — which weights mortgage interest, council tax, and motor fuels more heavily — doesn't get the same downward push from the price cap. RPI averaged 3.8% in Q1 2026 and sat at 4.1% in March. The April figure almost certainly stayed elevated, driven by the 23.0% annual surge in motor fuel prices — the highest since September 2022. That RPI-CPI spread, typically 0.5-0.8 percentage points, compounds significantly over a 20- or 30-year gilt holding period.

For most of the 2010s, index-linked gilt real yields were negative. You were paying the government for the privilege of inflation protection. That era is firmly over — but the curve has shifted shape in an important way since the May refresh.

Real yields from the UK index-linked gilt market on 15 June 2026:

Three things stand out from this curve compared to a month ago.

First, short-dated linkers have crossed into positive territory. The 2028 (T28) now yields +0.06% real — barely positive, but no longer negative. A month ago T28 was at -0.23% and T27 at -0.69%. The entire front end of the curve has shifted up, meaning you no longer pay for the privilege of short-dated inflation protection.

Second, the 10-year benchmark has barely budged — 1.68% versus 1.65% in May. The peace deal has compressed nominal yields but left real yields steady, which tells you the market is stripping inflation expectations out of the nominal side rather than repricing the real return.

Third, the ultra-long end has flattened. The 2050s and 2060s have come in slightly from their peaks of 2.35%. The curve peak sits around the 2048-2050 maturity zone at roughly 2.33% real, down from 2.35% a month ago. Long-dated real yields remain historically extraordinary — buying the 2050 linker locks in RPI + 2.33% for a quarter-century — but the direction of travel matters.

What changed versus May? Nominal gilt yields fell roughly 16 basis points on the 10-year benchmark as peace hopes were priced in. Real yields on linkers actually ticked up 3 basis points over the same period. The market is saying: inflation risks are lower (cheaper oil, supply chains reopening), but the real return investors demand for locking up capital in sterling for a decade hasn't changed. For a detailed meeting-by-meeting MPC breakdown, see our BoE rate-cycle analysis.

With conventional 10-year gilts at roughly 4.91% and the 2036 linker at 1.68% real, the implied breakeven inflation rate is approximately 3.23%. If RPI averages above 3.23% over the next decade, linkers win. Below it, conventional gilts win. RPI has not been below 3.23% on a sustained annual basis since 2021 — but the peace deal changes the odds.

The more practical comparison is cash ISA vs linker. Take £20,000 — the full ISA allowance — and assume a 10-year horizon.

Option A: best 1-year fixed cash ISA at roughly 4.50% AER, tax-free in the wrapper. (Top rates have drifted down from 4.65% in May as banks price in rate-cut expectations following the peace announcement.)

• Nominal value after 10 years, assuming rates stay at 4.50% and you roll annually: £20,000 × 1.045¹⁰ = £31,059
• If RPI averages 3.5%, real value = £31,059 / 1.035¹⁰ = £22,025 in today's money
• If RPI averages 3.0% (closer to a peace-dividend scenario), real value = £31,059 / 1.03¹⁰ = £23,102
• If RPI averages 4.0% (closer to pre-peace trend), real value drops to £20,972

Option B: 10-year index-linked gilt at 1.68% real, held in the same ISA wrapper.

• Real value after 10 years (guaranteed): £20,000 × 1.0168¹⁰ = £23,622 in today's money
• This number does not change if RPI is 2%, 4%, or 8%. The real return is locked.

The crossover post-peace-deal. At 4.50% nominal vs 1.68% real, the cash ISA wins only if RPI averages below ~2.77% over the decade. That is lower than the ~2.95% breakeven from May — because cash ISA rates have started to fall while the linker's real yield has actually risen slightly. The peace deal, counterintuitively, has made the case for linkers stronger relative to cash.

RPI has not been sustainably below 2.77% since before the pandemic. Even if the peace deal brings oil back to $70 and the Bank resumes cutting to 3.00%, getting RPI below 2.8% for a full decade requires a disinflationary regime the UK hasn't seen since the early 2010s. The structural factors — NHS backlogs, defence spending, the transition to net zero, labour shortages post-Brexit — don't disappear with a peace deal.

Tax treatment favours linkers for higher-rate taxpayers held outside an ISA. All gilts are exempt from capital gains tax, and the inflation uplift on principal counts as capital gain, not income. Only the real coupon is taxed as income. Hold in an ISA or SIPP and even that disappears. For a complete tax wrapper comparison, see our investing hub.

Picking the right point on the curve matters more than ever. Two real choices, both £10,000 invested today.

Choice A: 0⅛% IL Treasury Gilt 2028 (T28). Two years and two months to maturity, real yield +0.06%. Clean £100.15, dirty £148.12. £10,000 nominal costs roughly £14,812 to acquire. You earn RPI inflation plus a negligible 0.06% per year. With RPI running somewhere north of 3.5%, your nominal return is around 3.6-4.2% — decent, but you are capping your upside to whatever inflation does in two years.

Choice B: 0⅛% IL Treasury Gilt 2036 (TG36). 10 years and 5 months to maturity, real yield +1.68%. Clean £85.14, dirty £135.18. £10,000 nominal costs roughly £13,518 to acquire. You earn RPI inflation plus 1.68% per year for a decade.

Simulate three RPI scenarios:

The shorter linker only beats the longer one if you can roll the proceeds in August 2028 into something paying significantly more than today's 1.68% real. In a peace-dividend scenario where inflation collapses and real yields fall further, you'd be rolling into a worse deal. In a scenario where real yields rise further, you win — but you've taken two years of barely-positive returns to get there.

The TG36 buyer outsources that call entirely and pockets a guaranteed 1.68% real for ten years. After today's peace deal, locking in that guarantee looks wiser — not because inflation expectations have collapsed, but because they might, and a decade of certainty at 1.68% real is a good insurance policy against any outcome.

The price-volatility caveat still applies. TG36 trades at £85.14 clean. If 10-year real yields rise another 50 basis points, that price falls roughly £4.50. Hold to maturity and you receive the inflation-uplifted £100 nominal regardless — but you must stomach the mark-to-market. Long-dated linkers are far worse: the 2056 issue trades around £53, and the 2068 issue around £46. Only buy them if you can hold or accept severe mark-to-market swings. See why gilts can hammer your capital for the worked downside.

The announcement on 15 June 2026 that the US and Iran have reached a deal is the most significant macro event for gilt investors since the Strait of Hormuz closure on 2 March. Oil prices have fallen sharply and European stock markets hit record highs on the news. The Guardian reported that Brent crude dropped to a three-month low within hours of the announcement.

For index-linked gilt investors, this cuts in three directions.

First, the short-term disinflation impulse is real. The April 2026 ONS data already showed motor fuel prices at crisis levels — petrol at 156.8p and diesel at 190.0p, the highest since late 2022. Those numbers were driven by the Iran supply shock. If oil normalises toward $70-80, the next few CPI and RPI prints will fall. The June MPC meeting on 19 June now looks almost certain to hold at 3.75%, and the probability of a cut later in 2026 has risen sharply. Lower inflation means lower nominal gilt yields — which means higher linker prices for anyone who already owns them.

Second, the structural inflation story hasn't gone away. The peace deal doesn't rebuild Ukraine, doesn't solve the UK's chronic labour shortage, doesn't unwind the £150 billion of NHS backlog spending, and doesn't reverse the defence budget increases that every major party has committed to. These are fiscal, not geopolitical, drivers of UK inflation — and they persist regardless of what happens in Tehran. Core CPI was still 2.5% in April even as headline fell to 2.8%. Services inflation, the Bank of England's preferred domestic gauge, was 3.2% — still well above the 2% target-consistent rate.

Third, the breakeven compression creates an opportunity. The implied breakeven rate has fallen from 3.42% to roughly 3.23% as the market prices peace. If you believe RPI will average more than 3.23% over the next decade — and remember, RPI has structural features that keep it 0.5-0.8pp above CPI — then buying linkers today at 1.68% real with nominal yields having fallen captures a better entry point than May offered. You are being paid the same real yield but with lower nominal yields providing a tailwind to the price.

The April 2026 FRED reading of 4.82% already captured the pre-peak of the Iran crisis. Since then, peace expectations have pulled the 10-year down toward 4.91% — but the FRED series runs a month behind and won't show the full peace-deal drop until the May print. For a real-time view, the dividenddata.co.uk gilt page updates daily.

For our full analysis of the Iran conflict's impact on UK investor portfolios, see how the Iran conflict killed the rate-cut cycle.

Three routes to index-linked gilt exposure, each with different trade-offs.

Individual gilts via a broker. Hargreaves Lansdown, AJ Bell, interactive investor, and most UK stockbrokers let you buy specific index-linked gilts on the secondary market. You choose the maturity, lock in the real yield, and hold to redemption. Dealing fees run £5-12 per trade. The dirty price is what shows up on your contract note: TG36 charges roughly £135 per £100 nominal even though the clean price quoted is £85. The difference is accumulated inflation since 2013 — you are not overpaying, you are buying the right to receive that inflation uplift at maturity.

The DMO Purchase and Sale Service. The UK Debt Management Office, administered by Computershare, allows approved investors to buy gilts directly. Slower and less convenient than a platform, but viable for buy-and-hold investors. For step-by-step instructions, see our practical gilt buying guide.

Index-linked gilt funds and ETFs. The iShares UK Index Linked Gilts ETF and Vanguard UK Inflation-Linked Gilt Index Fund provide diversified exposure across maturities. Simplicity and liquidity are the upside. The downside: no maturity date. A fund holds a rolling portfolio, so you never lock in a real yield — you are always exposed to changing real rates. Fund investors who bought in 2021 suffered capital losses through 2022-23 even while the underlying inflation protection worked as designed. If your goal is to lock in today's 1.68% real for a decade, you need individual gilts — not a fund.

Tax wrappers matter. Gilts fit inside a Stocks & Shares ISA or SIPP. The CGT exemption already covers the inflation uplift on principal, so the main wrapper benefit is sheltering the (tiny) income. For a 40% taxpayer holding £50,000 nominal of linkers outside a wrapper, the annual tax drag is a few pounds on those small coupons — but it compounds. Our gilts hub tracks live yield data and platform fee comparisons.

Minimum investment is as low as one penny nominal, though platforms set practical minimums around £100.

The government has confirmed that from February 2030, RPI will be aligned with CPIH for all index-linked gilts. This isn't speculation — the ONS has confirmed the change and the Supreme Court ruled in 2022 that the government has legal authority to make it.

For any linker maturing before 2030 — the 2027, 2028, and 2029 issues — this is irrelevant. For everything longer, your inflation measure switches from RPI to CPIH partway through the gilt's life. The gap matters: RPI averaged 3.8% in Q1 2026; CPIH averaged 3.2%. That 0.6 percentage point difference, compounded over 20 years, reduces the terminal value of a linker by roughly 12% in real terms.

Take TG36, maturing in November 2036. Years 1 through 4 (2026-2030) will be indexed to RPI. Years 5 through 10 (2030-2036) will be indexed to CPIH — a permanently lower number. The headline real yield of 1.68% assumes RPI throughout, which overstates the actual return you will receive. A rough adjustment: if CPIH runs 0.6 percentage points below RPI and applies for 6 of the 10 remaining years, the effective real yield is closer to 1.32% rather than the quoted 1.68%.

This doesn't make TG36 a bad investment — 1.32% real risk-free is still better than anything cash or conventional gilts offer on a real basis. But it means the 10-year linker is not as good a deal as the headline number suggests, and it makes shorter-dated linkers (2029, 2031) relatively more attractive because a smaller proportion of their remaining life falls under the CPIH regime.

The reform creates an odd wrinkle: a linker ladder spanning 2029, 2031, 2036, and 2044 gives you progressively more exposure to the CPIH haircut as you go further out. The 2031 issue gets only one year of CPIH before maturity; the 2044 gets fourteen years. Price this explicitly when constructing a ladder. For a broader look at gilt strategy, see our comprehensive gilt yields guide.

Buy if you are within 10-15 years of retirement and want to guarantee your pot keeps pace with living costs. A ladder of linkers maturing in sequence gives you inflation-proofed income without equity risk. At 1.68% real on the 10-year, you are being paid to take the protection — a dramatically better deal than the negative real yields of the 2010s. The peace deal hasn't changed this: even if inflation falls to 2.5%, 1.68% real is a genuinely useful return from a risk-free asset.

Buy if you are a higher-rate or additional-rate taxpayer looking for tax-efficient fixed income. The CGT exemption on the inflation uplift makes linkers more efficient than corporate bonds or savings accounts where interest is fully taxed. Our savings hub compares after-tax alternatives.

Buy if you believe the peace deal is temporary or partial. The history of Middle East diplomacy suggests agreements unravel. If you think oil prices will rebound and inflation will re-accelerate, buying linkers today — while nominal yields have already fallen on peace hopes — locks in the protection before the market reprices the risk.

Don't buy if you might need the money before maturity. Index-linked gilt prices swing violently — the 2056 issue trades around £53, the 2068 issue around £46, both well below par. Selling early in any environment crystallises real losses. The peace deal has given a short-term boost to linker prices as nominal yields fall, but that works both ways.

Don't buy if you are convinced the peace deal marks a return to the 2010s disinflationary regime. If you think RPI averages 2% or less for the next decade — which hasn't happened since the 1950s outside the post-GFC deflation scare — conventional gilts at 4.91% will massively outperform. You will have locked in 1.68% real when you could have earned 3%+ above actual inflation.

Don't buy if you want simplicity. The RPI lag, the dirty/clean price distinction, the 2030 reform adjustment, and the peace-deal repricing of breakevens make linkers genuinely complex. If that is off-putting, a diversified gilt fund handles the complexity for a small ongoing charge. For a balanced view, read the debate: gilts at 5% vs your savings account and the case against buying gilts.

This article is for informational purposes only and does not constitute financial advice. You should seek independent financial advice before making any investment decisions.