How we calculate every number on YieldSmart.

Data and timeliness

During London Stock Exchange trading hours prices are indicative mid prices from the LSE, refreshed about every 10 minutes — so they can be up to ~10 minutes old, and they are not dealing prices. Outside trading hours each gilt shows the last mid price of the previous session (or, if there was none, its last trade). Every price is checked against that gilt's previous closing price (from YieldSmart's own daily record) and rejected if it is more than 10% away — a gilt that fails, or that the LSE doesn't list, shows its last closing price instead; the date the prices are from is shown on every page. Always check the live price with your broker before dealing.

Instrument details — each gilt's coupon, maturity date, coupon dates, first issue date and ISIN — come from the UK Debt Management Office's register of gilts in issue, checked for changes every day. Yields, net yields and durations are recalculated from the latest price.

Price history charts (free on every gilt page) use daily closing prices (YieldSmart's own record of London Stock Exchange closes, plus five years of end-of-day history from our data provider), with each day's yields recalculated from that day's price. The 5-year view shows one close per week; shorter views show every trading day. The latest point on a chart is today's price, labelled as such. A few recently issued gilts start their history from when we began recording them.

The historical yield curve uses the Bank of England's estimated nominal spot-rate curve, published daily. These are zero-coupon spot rates, which differ from redemption (par) yields, most visibly at the long end. Contains public sector information licensed under the Open Government Licence v3.0.

Net yield — after-tax yield to maturity

The headline gross yield is the conventional gross redemption yield (yield to maturity), before tax. Our net yield is the internal rate of return (IRR) of the gilt's after-tax cash flows, held to maturity:

• Each semi-annual coupon is taxed at your income tax rate (the coupon is savings income) — at the rate in force when it is paid. Savings-income tax rates rise by 2 percentage points from 6 April 2027 (20/40/45% become 22/42/47%, UK-wide), so coupons paid from that date are taxed at the higher rate.
• The redemption at £100 is left untaxed — the capital gain from a sub-par price up to par is exempt from capital gains tax, because gilts are CGT-exempt.
• On the first coupon, only the interest earned while you hold the gilt is taxed: the accrued interest you paid for in the price is not taxed again (the Accrued Income Scheme). A gilt bought ex-dividend has no first coupon.

We discount on exactly the same basis as the gross yield — actual coupon dates, T+1 settlement, the dirty price and the fractional period to the next coupon — so at 0% tax the net yield equals the gross yield.

This is why a low-coupon gilt trading below par shows a higher net yield for higher-rate taxpayers — most of its return is the tax-free pull to par rather than taxable coupon.

Savings Rate Equivalent

The Savings Rate Equivalent is the gross yield a fully-taxable investment (a savings account, an at-par bond) would need to pay to match the gilt's net yield, at your tax rate. Savings interest is taxed at the same rates — including the 2-point rise from 6 April 2027 — so we use your rate averaged over the gilt's remaining life (time-weighted between today's rate and the post-April-2027 rate):

It is the fair, like-for-like comparator against a savings rate or deposit.

“Need it by” — return to your date

On the gilt table you can say when you need the money. We then rank the conventional gilts by their after-tax return to that date, as a yield a year (on the same basis as the net yield):

• On time — matures in the six months before your date: the coupons and the £100 redemption, after tax, as in the net yield.
• Early — matures earlier: after it repays, the cash is assumed to sit in a savings account until your date, earning the Bank of England average easy-access rate after your tax. So a gilt that repays a few weeks early barely loses anything, and one that repays years early is fairly marked down.
• After your date — you would have to sell it on your date. We estimate that price by valuing the gilt at the yield today’s curve gives for the time it will have left (“rolling down the curve”). That price is not guaranteed, so these gilts are ranked after the cash-certain ones and we show how much the price would move if yields were 1% different.

Coupons are taxed at your band (rising by 2 points from 6 April 2027), with the Accrued Income Scheme on the first coupon and on any sale; the gain to £100 or on a sale is CGT-free. Index-linked gilts aren’t ranked, because their cash depends on future inflation.

Charts (Premium)

Yield scatter: today's dots use today's prices, exactly as the gilt table. The comparison dots use each gilt's closing price on the chosen date (or the last close before it, if that was a weekend or holiday), with the yield worked out as of that date — so the years to maturity, the next coupon and, for net yield, the tax rate on each coupon are all as they were then. Duration is Macaulay duration on the same cashflows. Past dates include the conventional gilts repaid since then (from the DMO's list of redeemed gilts, with their closing prices up to the day before repayment), so the short end looks as it did on that date; index-linked gilts repaid since aren't included. The same repaid gilts fill the short end of the actual-gilts curve-steepness chart. The optional Bank of England line is its fitted nominal spot curve at 2, 5, 7, 10 and 30 years — a smoothed, before-tax reference, not a gilt you can buy. Index-linked gilts show real yield for the 3-month-lag gilts; the two older 8-month-lag gilts are left out.

Compare gilts uses the same daily closes and per-day yields as the price history on each gilt page; with two gilts, the gap is the first minus the second on each day (basis points for yields, £ per £100 for price) or the first divided by the second. Curve steepness is the difference between two maturities (10y−2y, 30y−10y, 5y−2y, 10y−5y or 30y−2y), one reading a week, measured either on the Bank of England's nominal spot curve or from the actual gilts: for each maturity, the yield is interpolated between the two conventional gilts either side of it from that week's closing prices, gross or after tax at 20/40/45%. Where the nearest gilts either side are far apart (some older short-maturity readings, whose gilts have since been repaid), no reading is shown. Gilts vs cash compares a gilt's yield to maturity on each day, before and after income tax, with the top-paying easy-access savings account at the time, before and after the same tax. No free historical series of best-buy rates exists, so we record MoneySavingExpert's top easy-access pick from each monthly snapshot of its savings guide (via the Internet Archive, from September 2021), skipping cash ISAs and accounts with a balance cap under £10,000, fewer than about four withdrawals a year, a linked or paid current account or a monthly pay-in condition; a 12-month introductory bonus counts, because a saver switching that month received it. Bank Rate (IUDBEDR) is shown before tax for reference, and the Bank of England's average rate across all instant-access accounts (IUMB6VJ) can be added. Neither side includes your Personal Savings Allowance.

Accrued interest

When you buy a gilt between coupon dates you also pay the interest that has built up since the last coupon (the difference between the clean price quoted and the dirty price you settle). We calculate accrued interest to a T+1 settlement date on an actual/actual day-count basis — actual days since the last coupon divided by the actual days in the coupon period, in UTC.

T+1 skips weekends and UK bank holidays. Inside the ex-dividend period (the 7 business days before a coupon) accrued interest is negative: the seller keeps the coming coupon, so you pay less than the clean price.

Newly issued gilts. A gilt's first coupon only pays for the days from its first issue date, so it is usually short (for example the 4⅝% Treasury Gilt 2030, issued 11 September 2026, pays £0.904891 per £100 on 22 November 2026 rather than the usual £2.3125). Until that first coupon is paid, accrued interest runs from the issue date and the first coupon is the reduced amount, as the DMO publishes it.

Modified duration

Modified duration measures price sensitivity to yields: roughly, the percentage change in price for a 1% change in yield. We use the standard semi-annual formula — Macaulay duration on the gilt's actual remaining cash flows (real coupon dates, the fractional period to the next coupon), discounted at the gross yield, divided by (1 + y/2):

Longer-dated gilts have higher duration and so larger price swings when interest rates move — the main risk for a gilt held and sold before maturity.

Tax assumptions — read this

We apply current UK tax rules as they affect a private individual holding gilts directly (not through a fund or wrapper):

• Coupon income is taxed at your marginal income tax rate (0%, 20%, 40% or 45%) — rising to 22%, 42% and 47% for coupons paid from 6 April 2027 (announced in the 26 November 2025 Budget). Price history charts apply today's rules to every date, so their net yields are what each past price would return under current tax law.
• Capital gains are exempt — the gain to maturity, or on any earlier sale, is free of CGT (though interest accrued since the last coupon is taxed as income on a sale, under the Accrued Income Scheme). Equally, a loss on a gilt is not allowable for CGT, so the apparent "loss" on an above-par gilt held to maturity cannot be used against other gains.

ISAs and SIPPs

Inside an ISA or SIPP there is no income tax on coupons, so the after-tax yield is simply the gross yield. Compare gilts and the Ladder builder let you choose General account, ISA or SIPP; everywhere else assumes a general (taxable) account.

Index-linked gilts

For index-linked gilts with a 3-month indexation lag (all issued since 2005) we show the real yield — the inflation-adjusted yield, computed from the quoted real price with no inflation assumption — and break-even inflation: the yield of a conventional gilt of the same maturity (interpolated along the curve) minus the real yield. If RPI inflation averages more than the break-even, the index-linked gilt does better. The two older 8-month-lag gilts (2030 and 2035) can only be given a real yield by assuming future inflation, which we show alongside (2%). The inflation uplift on the principal is CGT-free; the coupon (including its inflation uplift) is taxable income.