NS&I Premium Bonds are one of the most popular savings products in the UK, holding money for millions of savers. But unlike a normal savings account, Premium Bonds pay no guaranteed interest at all — instead, every £1 bond is entered into a monthly prize draw. Understanding the maths behind that draw explains why some people do very well and others barely see a return.
How Premium Bonds actually work
You buy bonds at £1 each, up to a maximum holding (set by NS&I, currently £50,000 per person). Each eligible bond number is entered into a monthly draw for tax-free prizes ranging from £25 up to two £1 million jackpots. There's no interest paid directly — instead, NS&I sets an annual "prize rate", which represents the average return across all bondholders if you take the whole pot of prize money and divide it by the total number of bonds in the draw.
Why the prize rate isn't what you'll actually get
The prize rate is an average, not a guarantee. Because most of the prize fund is made up of many small prizes and a tiny number of very large ones, most bondholders in any given month win nothing, some win a small prize, and a very small number win a life-changing sum. This is fundamentally different from savings interest, which is paid to everyone in proportion to their balance.
| Outcome | Roughly how common |
|---|---|
| No prize in a given month | The large majority of bond numbers, most months |
| Small prize (e.g. £25–£100) | Most winners fall in this range |
| Large or jackpot prize | Extremely rare — a tiny fraction of bondholders |
Why pot size matters so much
Because prizes are drawn per bond number and each £1 bond is one entry, the more bonds you hold, the more entries you have and the closer your actual return tends to track the headline prize rate over time — in the same way that flipping a coin many times gets you closer to a 50/50 split than flipping it a handful of times. With only a few hundred pounds in bonds, it's entirely normal to go many months, or even years, without winning anything at all, while someone holding the maximum balance is statistically likely to win something most months, even if it's usually a small prize.
Comparing Premium Bonds with a standard savings account
- Guaranteed vs. variable. A normal easy-access savings account pays a known interest rate on every pound, every year. Premium Bonds pay nothing to any individual bond in a month it doesn't win.
- Tax treatment. Premium Bond prizes are entirely tax-free, regardless of your other income or savings interest, which can matter for higher and additional-rate taxpayers who have used up their Personal Savings Allowance.
- Capital security. Your original money is backed by the UK government via NS&I, similar in security terms to top-tier FSCS-protected savings, but without any FSCS limit since NS&I deposits are 100% government-backed regardless of amount.
- Liquidity. You can typically cash in bonds and withdraw, though it can take a few working days, similar to some easy-access accounts.
Common misconceptions
- "The prize rate is what I'll earn." It's an average across the whole pool — smaller holdings should expect below-average, lumpy, unpredictable returns, both above and below that headline figure over time.
- "Old, unwon bonds are less likely to win." Each monthly draw is independent; a bond doesn't become "due" a prize.
- "Winning depends on skill or timing of purchase." It's a random draw; when in the month you buy makes no difference to your odds once bonds are eligible.
What to do next
Premium Bonds can suit money you want to keep completely safe with a small chance of a notable win and full tax-free treatment, but if you're relying on predictable income or want to maximise expected return on a modest sum, compare the prize rate against current top easy-access and fixed-rate savings rates — for smaller balances, guaranteed interest will usually give a more reliable outcome.