Gilt vs Savings vs ISA - Best Home For Your Cash

For higher-rate and additional-rate taxpayers holding cash outside an ISA, a low-coupon gilt is often the better choice because most of its return comes as a capital gain that is exempt from Capital Gains Tax. A savings account or money-market fund hands you the same headline interest but taxes all of it as savings income, so a 4.25% account can shrink to 2.55% net for a 40% taxpayer. If you have ISA allowance free, a cash ISA usually beats both because the interest is entirely tax-free. The right answer depends on your tax band and the exact rate each product pays today.

Gilt vs savings calculator: which wins after tax?

This is the question the gilt vs savings calculator exists to settle. On paper, a savings account paying 4.25% looks identical to a gilt yielding 4.25% to maturity. After HMRC takes its cut, they can be worlds apart. The reason is structural: gilts (UK government bonds) and savings accounts are taxed under completely different rules, and that difference grows the higher your marginal rate.

For an individual, a gilt's price gain between purchase and maturity is exempt from Capital Gains Tax. Only the coupon - the fixed interest the gilt pays - is taxed, as savings income at your marginal rate. A savings account has no such shelter: every penny of interest is taxable income once you exhaust your Personal Savings Allowance. So when you compare a gilt vs savings account, you are really comparing a partly tax-free return against a fully taxable one.

Key facts

• Gilt capital gains are CGT-exempt for individuals - the gain from a sub-par price up to the £100 redemption value is tax-free.
• Gilt coupons are taxed as savings income at 20% / 40% / 45% in 2026/27 (rising to 22% / 42% / 47% from April 2027).
• Savings interest is fully taxable at your marginal rate, after the Personal Savings Allowance of £1,000 (basic), £500 (higher) or £0 (additional).
• Cash ISA interest is entirely tax-free, within the £20,000 annual ISA allowance.
• Premium Bond prizes are tax-free but pay an average prize rate, not a guaranteed return - they are NS&I and government-backed.
• The winner changes with your tax band. A low coupon gilt can quietly beat a higher-headline savings account once tax is applied.

How does a gilt's tax treatment differ from a savings account?

A gilt has two moving parts: the coupon and the capital movement. Buy a gilt below its £100 par value and hold it to maturity, and the climb back to £100 is a capital gain - and for individuals that gain carries no Capital Gains Tax. The coupon, meanwhile, is treated exactly like bank interest: savings income, taxed at your marginal rate.

This is why a low coupon gilt is the quiet hero of after-tax investing. Engineer the package so that little of the return is taxable coupon and most of it is the CGT-free pull to par, and a higher-rate taxpayer keeps far more of the total return. A savings account cannot do this. It pays interest and only interest, and that interest is taxable in full once your Personal Savings Allowance is used up - which, for a higher earner with a decent balance, happens fast.

The headline rate tells you what you earn; the tax treatment tells you what you keep. Two products quoting 4.25% can leave a 40% taxpayer with 4% in one hand and 2.55% in the other.

After-tax returns compared: savings vs gilt vs ISA vs Premium Bonds

The table below shows how the same broad pot of cash performs across four homes, by tax band. Figures are illustrative and assume the Personal Savings Allowance is already used up by other interest. The gilt column reflects a low-coupon gilt where most of the return is the CGT-free gain to par.

Read the higher-rate column carefully. The savings account collapses to 2.55%, while the low-coupon gilt holds near 4% because its return is overwhelmingly a tax-free capital gain. The cash ISA's 4.10% is fully protected at every band - which is why, if you have allowance spare, it is often the simplest win. Premium Bonds sit apart: their return is tax-free but it is an average, so a saver with a modest balance may earn nothing in a given period.

Gilt vs ISA: do you even need the CGT shelter?

Comparing a gilt vs ISA is a different question from gilt vs savings. A cash ISA already makes interest tax-free, so a gilt's CGT exemption brings no extra advantage inside the £20,000 ISA wrapper - the wrapper has done the sheltering for you. The decision then comes down to which pays the better rate and which you can access when you need to.

Outside an ISA, the calculus flips. Once your ISA allowance is spent, or if you are parking a sum far larger than £20,000, the gilt's CGT-free gain becomes genuinely valuable. For someone holding six figures of taxable cash, a ladder of low-coupon gilts can be the most tax-efficient home available short of further pension contributions. Our ISA calculator and savings interest tax calculator let you see exactly where your allowances run out.

How the gilt vs savings calculator works

The calculator takes the messy, band-by-band tax maths and turns it into a single after-tax number you can act on. You enter four things: the amount of cash, your tax band, the savings rate on offer, and the gilt you are weighing up (its price, coupon and maturity). From there it does the work a spreadsheet would, but with the right tax rules baked in.

• Savings side: it applies your Personal Savings Allowance (£1,000, £500 or £0), then taxes the rest of the interest at your marginal rate to give a net yield.
• Gilt side: it splits the return into taxable coupon and CGT-exempt capital gain, taxes only the coupon, and reports the blended after-tax yield to maturity.
• ISA and Premium Bonds: it shows the cash ISA return tax-free, and flags that Premium Bonds pay an average prize rate rather than a guaranteed one.
• The verdict: it ranks the options by net return for your band, so you can see the best place for cash after tax at a glance.

The numbers feeding the gilt side come from public gilt data - coupon, maturity and clean price are all published by the UK Debt Management Office at dmo.gov.uk. For the deeper gilt mechanics, pair this tool with our gilt yield calculator to confirm the yield to maturity before you commit.

Worked example: a 40% taxpayer with £50,000

Suppose a higher-rate taxpayer has £50,000 sitting outside any wrapper and has already used the £500 Personal Savings Allowance on other interest. A 4.25% savings account pays £2,125 of interest - but at 40% tax that nets just £1,275, an after-tax yield of 2.55%. The same money in a low-coupon gilt, where the bulk of the return is the CGT-free climb to par, can net close to 4%, roughly £2,000. That is a difference of around £725 a year on the same £50,000, purely from how the return is taxed.

For a higher-rate taxpayer, the gilt isn't winning by paying more - it's winning by being taxed less.

Spread that decision across a maturity schedule and the gap compounds. A gilt ladder calculator shows how staggering several gilts keeps cash accessible while preserving the tax advantage year after year.

Choosing the right home for your cash

There is no single best place for cash after tax - there is only the best place for your band, balance and time horizon. Work through it in this order:

• Fill the ISA first. If you have any of the £20,000 ISA allowance left, a competitive cash ISA gives tax-free interest at every band. Check the headroom with the ISA calculator.
• Basic-rate taxpayer with a small balance? A plain savings account may be fine - your £1,000 Personal Savings Allowance could shelter most or all of the interest. Confirm with the savings interest tax calculator.
• Higher or additional-rate, taxable cash beyond your ISA? A low coupon gilt usually wins, because the CGT-free gain dodges the tax that guts a savings account.
• Want a flutter with zero tax and capital security? Premium Bonds suit some savers, but remember the return is an average prize rate, not guaranteed - the Premium Bonds calculator shows the realistic odds.
• Worried about inflation? An index-linked gilt ties both coupon and capital to the Retail Prices Index; see the index-linked gilt calculator.

Two practical reminders. First, the gilt advantage is strongest when the coupon is low and the price is well below par - a high-coupon gilt is mostly taxable income and behaves more like a savings account. Second, tax rates are moving: savings and coupon income is taxed at 20% / 40% / 45% in 2026/27, but rises to 22% / 42% / 47% from April 2027, which widens the gilt's edge further. You can check your allowance position directly with HMRC at gov.uk/apply-tax-free-interest-on-savings and review the ISA rules at gov.uk/individual-savings-accounts.

When a savings account still beats a gilt

None of this makes gilts a default. A savings account or cash ISA wins outright when you need instant access, when your balance is small enough that the Personal Savings Allowance soaks up the tax, or when savings rates simply sit above gilt yields. Gilts also carry interest-rate risk if you sell before maturity - the CGT exemption protects the gain but does nothing to guarantee the price on a given day. The honest answer the calculator gives is rarely "always gilts." It is "for your band, your balance and today's rates, here is the home that keeps the most."

This article is general information about UK tax for the 2026/27 tax year, not personal financial or tax advice. Gilt prices can fall as well as rise, and tax treatment depends on your circumstances. Check current rates and confirm your position with a qualified adviser or HMRC before investing.