UK gilts explained: how government bonds connect to your mortgage rate

What the source announced

A gilt is a UK Government liability denominated in sterling, issued by HM Treasury and listed on the London Stock Exchange (DMO, About Gilts). The term 'gilt-edged' captures the instrument's defining characteristic as an investment: the British Government has never failed to make interest payments or principal payments on gilts as they fall due (DMO, About Gilts).

The gilt market comprises two types of securities — conventional gilts and index-linked gilts (DMO, About Gilts). A conventional gilt is a liability of the government under which it guarantees to pay the holder a fixed cash payment (coupon) every six months until the maturity date, at which point the holder receives the final coupon payment and the return of the principal (DMO, About Gilts). The price of a conventional gilt is quoted per £100 face value (DMO, About Gilts).

The coupon rate on a conventional gilt typically reflects the market interest rate at the time of first issuance (DMO, About Gilts). The coupon itself indicates the cash payment per £100 nominal value that the holder will receive per year (DMO, About Gilts), paid in two equal semi-annual instalments on fixed dates.

The UK was one of the earliest developed economies to issue index-linked bonds to institutional investors, with the first issue taking place in 1981 (DMO, About Gilts). Index-linked gilts differ from conventional gilts in that both the semi-annual coupon payments and the principal repayment are adjusted in line with the UK Retail Prices Index (RPI) with a lag (DMO, About Gilts). Both coupons and the principal repaid on redemption are adjusted to account for accrued inflation since the gilt was first issued (DMO, About Gilts).

What this means for your mortgage

The coupon rate usually reflects the market interest rate at the time when the gilt is first issued. This is why fixed mortgage rates can move sharply even when the Bank of England base rate has not changed.

Index-linked gilt payments — coupons and principal alike — are adjusted for RPI inflation accrued since issuance (DMO, About Gilts). Their presence in the gilt market reflects that long-term UK borrowing costs are not insulated from the path of inflation: the same inflation-sensitive pricing environment that index-linked gilt cash flows inhabit is one that lenders weigh when setting rates on longer fixed-rate mortgage terms. Calculate your fixed-rate mortgage payments →

How gilt yields feed into fixed mortgage rates

Lenders writing two-, five- or ten-year fixed-rate mortgages do not fund those loans from the Bank of England base rate directly. They fund them on the sterling swap market, exchanging variable cash flows for fixed ones over the term of the deal (Bank of England, Bank Rate). Swap rates of a given maturity track gilt yields of the same maturity, because both are sterling fixed-income instruments competing for the same institutional cash.

The chain reads: gilt yield → swap rate → headline fix. A move in the five-year gilt yield typically feeds into the five-year swap rate over the following days, and the cheapest five-year fixed mortgage deals reprice shortly after — the DMO daily prices page is the canonical live reference for the gilt leg of the chain. This is why fixed mortgage rates can move sharply between Monetary Policy Committee meetings — the gilt market is repricing the expected path of Bank Rate before the MPC has met.

Conventional gilts versus index-linked gilts and Treasury bills

Three sterling government debt instruments sit alongside one another. Conventional gilts pay a fixed cash coupon every six months and return a fixed £100 of principal per gilt at the maturity date (DMO, About Gilts). Index-linked gilts adjust both the semi-annual coupon and the principal repayment in line with the UK Retail Prices Index with a lag; the UK was one of the earliest developed economies to issue index-linked bonds, with the first issue in 1981 (DMO, About Gilts). Treasury bills are short-dated discount instruments with maturities of typically one, three or six months, issued by the DMO at a discount to face value and redeemed at par (DMO, Treasury Bills). Medium-dated conventional gilts — the two- to ten-year tenors — are what mortgage swap pricing primarily tracks.

Who issues gilts and who buys them

HM Treasury is the legal issuer of gilts, but the operational work — auctions, syndications, switch tenders, settlement — is run by the UK Debt Management Office, an executive agency of HM Treasury established in April 1998. The buyer side splits into four groups. The Bank of England holds a large stock through its Asset Purchase Facility, the vehicle used for quantitative easing during the pandemic and now for active quantitative tightening. UK pension funds and life insurers buy long-duration conventional and index-linked gilts to match their liabilities. Foreign sovereigns and central banks hold a meaningful share as reserves. UK retail investors can buy directly via the DMO's Approved Group of Investors retail purchase service. A thinner buyer base lifts yields and, with them, mortgage rates.

What moves gilt yields

Four drivers move gilt yields on any given trading day. Inflation expectations come first: higher expected Consumer Prices Index or Retail Prices Index inflation pushes investors to demand a higher nominal yield to protect the real return on principal repaid at maturity (ONS, Inflation and price indices). The expected Bank of England policy path comes second: the more rate cuts the market prices in, the lower gilt yields drift (Bank of England, Bank Rate). Fiscal credibility sits third: market views on the sustainability of the UK's debt path feed directly into the term premium investors charge to hold longer-dated gilts. Supply and demand technicals close the list — heavier DMO issuance against weaker pension demand pushes yields up regardless of the macro picture.

Worked example: the 2022 mini-Budget gilt episode

The September 2022 mini-Budget is the textbook demonstration of the gilt → swap → mortgage chain. On 23 September 2022 the Chancellor announced unfunded tax cuts; over the following four trading days, 30-year nominal gilt yields rose by around 100 basis points as investors repriced UK fiscal credibility (Bank of England, Financial Stability Report). The price moves triggered margin calls on defined-benefit pension liability-driven investment (LDI) funds, forcing them to sell gilts into a falling market to meet the calls and accelerating the yield rise (Bank of England, Financial Stability Report). On 28 September 2022 the Bank of England announced an emergency temporary gilt purchase facility, capped at £65bn, to restore orderly market conditions and protect financial stability (Bank of England, Gilt market operation). Two-year sterling swap rates spiked alongside the gilt move, and mortgage lenders responded by withdrawing hundreds of fixed-rate products in the days that followed and repricing the rest sharply higher. The chain ran in a single week: fiscal announcement → gilt yields → swap rates → fixed mortgage rates.

Worked example: coupon cash flows on £10,000 nominal

The DMO conventions above turn into concrete cash flows once you fix the numbers. Take an illustrative conventional gilt with a 4% coupon, held at £10,000 nominal (face) value. The coupon indicates the cash payment per £100 nominal value per year, paid in two equal semi-annual instalments (DMO, About Gilts):

• Step 1: Annual coupon cash: £10,000 × 4% = £400.00.
• Step 2: Semi-annual instalments: £400.00 ÷ 2 = £200.00 every six months.
• Step 3: At maturity: the final £200.00 coupon plus the £10,000 principal returned in full.

For an index-linked gilt the same arithmetic runs through the RPI adjustment. If accrued inflation since first issue stands at 10%, each £200.00 instalment is uprated to £200.00 × 1.10 = £220.00, and the principal repaid at redemption becomes £10,000 × 1.10 = £11,000 — both coupon and principal are adjusted for accrued inflation, per the DMO mechanics quoted above.

Worked example: price against yield — buying below or above par

Gilt prices are quoted per £100 face value (DMO, About Gilts), and the market price is rarely exactly £100. Two purchases of the same illustrative 4%-coupon gilt show why price and yield move inversely:

• Bought at £95 per £100: £10,000 nominal costs £9,500. The £400 annual coupon is unchanged, so the running yield is £400 ÷ £9,500 = 4.21%, and redemption at par returns £10,000 against the £9,500 paid — a £500 capital gain on top.
• Bought at £105 per £100: £10,000 nominal costs £10,500. Running yield falls to £400 ÷ £10,500 = 3.81%, and redemption returns £10,000 against £10,500 paid — a £500 capital loss that the coupon income has to overcome.

The coupon never moves after issuance; the price does. A falling price is the same event as a rising yield — which is why "gilt yields rose" and "gilt prices fell" describe the same trading day, and why the swap rates that track those yields drag fixed mortgage pricing with them.

Worked example: what a swap-rate move does to a monthly mortgage payment

The gilt → swap → fix chain ends in a monthly payment, so the last link is worth pricing. Using the standard repayment formula (monthly payment = P × r × (1+r)^n ÷ ((1+r)^n − 1), with r the monthly rate and n the number of payments), compare a £200,000 repayment mortgage over 25 years at two illustrative fixed rates half a percentage point apart — the order of move the 2022 episode above produced inside a single week:

• At 4.5%: r = 0.045 ÷ 12, n = 300 → monthly payment £1,111.66.
• At 5.0%: r = 0.05 ÷ 12, n = 300 → monthly payment £1,169.18.

The 0.5 percentage point repricing costs £57.52 a month — £690.24 a year — on the same loan. A borrower whose fix completes before the reprice and one whose fix completes after it hold identical debts at different lifetime costs. Calculate your fixed-rate mortgage payments → at two candidate rates to see the same gap on your own loan size and term.

Where gilt yields and mortgage swap rates sit in mid-2026

By mid-2026 the gilt market is trading in an environment defined by Bank Rate held at 3.75% (Bank of England, 18 June 2026 MPC decision) and an ongoing Bank of England quantitative tightening programme (Bank of England, Bank Rate). Two- and five-year gilt yields move daily on inflation prints, MPC speeches, and DMO auction outcomes — the DMO daily prices page is the canonical live reference. Headline two- and five-year fixed mortgage rates typically price at a margin above the equivalent swap rate, the gap covering lender margin, credit losses, and operational costs.

Frequently asked questions about UK gilts

How do gilts affect my mortgage?

Gilt yields set the floor for sterling swap rates, and swap rates set the floor for fixed mortgage rates. When the five-year gilt yield rises, the five-year swap rate rises within days, and the cheapest five-year fixed mortgage deals follow (Bank of England, Bank Rate). The chain runs independently of the Bank of England base rate decision cycle.

What is a coupon on a gilt?

The coupon is the fixed cash interest payment a conventional gilt pays per £100 of nominal value, expressed as an annual rate and paid in two equal semi-annual instalments on set dates (DMO, About Gilts). The coupon rate is set at issuance to reflect the prevailing market interest rate and does not change over the life of the gilt.

Can individuals buy gilts directly?

Yes — UK retail investors can buy gilts directly via the DMO's Approved Group of Investors retail purchase service. Gilts are also available on the secondary market through stockbrokers and can be held inside an ISA or a SIPP. Conventional and index-linked gilts of any maturity in issue are eligible for purchase.

What is the difference between gilt yield and gilt price?

Gilt yield and gilt price move inversely: when the price of a gilt falls, its yield rises, and the other way round. The yield is the implied annual return on the cash paid to buy the gilt at its current market price, given the fixed coupon and principal cash flows (DMO, About Gilts). Mortgage swap rates track yield, not price.

How did the 2022 mini-Budget affect gilts?

The 23 September 2022 mini-Budget triggered a roughly 100 basis point rise in 30-year gilt yields over the following four trading days, forced gilt sales by defined-benefit pension liability-driven investment funds, and prompted an emergency Bank of England temporary gilt purchase facility capped at £65bn announced on 28 September 2022 (Bank of England, Gilt market operation). Fixed mortgage rates rose sharply in the same week — see the worked example above.