Premium bonds feel safe and exciting. Investing can feel risky and dull. But over 10, 20, or 30 years, the numbers tell a very different story.
Premium bonds are a savings product issued by National Savings & Investments (NS&I), which is backed by HM Treasury. Unlike a traditional savings account, you do not earn interest. Instead, each £1 bond is entered into a monthly prize draw. Prizes range from £25 to £1 million, and all prizes are completely tax-free.
You can hold between £25 and £50,000 in premium bonds. Your capital is 100% safe — it is backed by the UK government, which means there is zero risk of losing your money. You can withdraw your bonds at any time, typically receiving the cash within 3 working days.
The current prize fund rate is approximately 4.4%. However, this figure is the total prize fund divided across all eligible bonds — it is not a guaranteed return. The rate is set by NS&I and can change at any time, usually in response to movements in the Bank of England base rate. The majority of the prize fund is distributed as £25 prizes, with a very small number of larger prizes including two £1 million jackpots each month.
The appeal of premium bonds is simple: zero risk to your capital, tax-free prizes, government backing, and the excitement of a monthly draw. For many UK savers, they feel like a "lottery you cannot lose" because your original stake is always returned in full.
Investing means putting your money into assets — typically shares, funds, or bonds — that have the potential to grow in value over time. The most common and straightforward approach for UK investors is to open a Stocks & Shares ISA and invest in a globally diversified index fund. Inside an ISA, all capital gains, dividends, and interest are completely tax-free, up to the annual allowance of £20,000.
Unlike premium bonds, investing carries risk. The value of your investments can go down as well as up, and you could get back less than you put in. This is especially true over short periods — in any given year, a global equity portfolio might fall 20% or more. However, over long periods of 10 years or more, diversified equity investments have historically delivered average annual returns of approximately 7-10% before inflation.
The mechanism that makes investing so powerful over the long term is compound interest. When your investments generate returns, those returns are reinvested, and they too generate returns. Over decades, this snowball effect can turn modest regular contributions into substantial wealth. This is the fundamental advantage investing has over premium bonds — your returns compound year after year.
With premium bonds, your prizes are paid out as cash. Unless you manually reinvest them, they do not compound. Even if you do reinvest prizes by buying more bonds, you are capped at £50,000 total. In a Stocks & Shares ISA, your returns are automatically reinvested and there is no cap on the total value of your ISA — only on how much new money you can add each year.
| Feature | Premium Bonds | Investing (S&S ISA) |
|---|---|---|
| Typical returns | Prize rate ~4.4% (but most holders earn far less) | 7-10% long-term average (global equities) |
| Risk | Zero — backed by HM Treasury, capital 100% safe | Medium to high — value can fall, especially short term |
| Tax | Tax-free — all prizes are completely tax-free | Tax-free inside an ISA; outside ISA: CGT at 18%/24%, dividend allowance £500 |
| Access | Withdraw within 3 working days | Sell within days, but selling during a downturn locks in losses |
| Maximum holding | £50,000 per person | £20,000/year in an ISA (unlimited outside ISA) |
| Protection | HM Treasury guarantee — 100% safe regardless of amount | FSCS up to £85,000 per provider (covers firm failure, not market losses) |
| Excitement factor | Monthly prize draw — chance of winning £1 million | Steady compounding — less exciting but more predictable over time |
| Best for | Risk-averse savers, short-term, higher-rate taxpayers | Long-term wealth building, younger investors, retirement |
The headline prize fund rate of ~4.4% is misleading for most holders. This rate represents the total prize pool divided by all eligible bonds. However, prize distribution is heavily skewed by the large prizes — two £1 million jackpots and a small number of £100,000, £50,000, and £25,000 prizes.
The reality for a typical holder looks very different. With £1,000 in premium bonds, you have roughly a 54% chance of winning nothing at all in any given year. Even with the maximum £50,000 holding, the median annual return is closer to 3.5-4.0%, not the headline 4.4%. The average is pulled up by the tiny minority of holders who win large prizes.
Think of it this way: if 1,000 people each hold £10,000 in premium bonds for a year, their average return might be 4.4% across the group. But the majority of individuals in that group will earn less than 4.4%, while a handful who win larger prizes will earn significantly more. Your personal return depends entirely on luck.
The following table shows what £20,000 could grow to under different scenarios. The premium bonds figures use the median expected return (~3.8%), while the investing figures use 7% average annual growth in a Stocks & Shares ISA.
| Time period | Premium Bonds (~3.8% median) | S&S ISA (7% avg) | Difference |
|---|---|---|---|
| 5 years | ~£24,100 | ~£28,100 | +£4,000 |
| 10 years | ~£29,100 | ~£39,300 | +£10,200 |
| 20 years | ~£42,300 | ~£77,400 | +£35,100 |
| 30 years | ~£50,000 (capped) | ~£152,200 | +£102,200+ |
Premium bonds figures use ~3.8% median return (below the headline prize rate). Growth beyond £50,000 is not possible with premium bonds as you cannot hold more than £50,000. S&S ISA assumes 7% average annual return. Both are tax-free. Past performance does not guarantee future results. Capital at risk when investing.
The gap is modest at 5 years — around £4,000. But by 20 years, investing has produced nearly double the wealth. At 30 years, the £50,000 cap on premium bonds becomes a hard ceiling, while the invested amount continues compounding freely to over £152,000. This is the fundamental long-term argument for investing: compound growth on higher returns, with no cap on the total.
These projections become even more striking when you consider regular monthly contributions. If you were adding £200 per month to each option, after 20 years the premium bonds holder (capped at £50,000) would stop being able to add more, while the ISA investor would have accumulated approximately £104,200 and still be compounding.
You are risk-averse. If the thought of your money falling in value keeps you awake at night, premium bonds are a perfectly valid choice. Zero risk, government-backed, and you will never lose a penny. For some people, the peace of mind is worth more than the potential extra returns from investing.
Short-term savings (under 5 years). If you need the money within 5 years — for a house deposit, a wedding, home renovations, or a large purchase — premium bonds offer a reasonable return without any risk of capital loss. The stock market can drop significantly over short periods, making it unsuitable for money you will need soon.
You have already maxed your ISA allowance. Once you have used your full £20,000 ISA allowance for the year, premium bonds are an attractive option for additional savings. Outside an ISA, savings interest and investment gains are taxable. Premium bond prizes are always tax-free regardless of amount, making them particularly efficient for surplus cash.
Higher-rate and additional-rate taxpayers. If you pay 40% or 45% tax, the tax-free status of premium bond prizes is especially valuable. A higher-rate taxpayer would need a savings account paying approximately 7.3% before tax to match a 4.4% tax-free return from premium bonds — and such rates are extremely rare. For top earners, premium bonds can be one of the most tax-efficient places to hold cash.
Emergency fund. Premium bonds make an excellent home for your emergency fund. The 3-day withdrawal period is slightly slower than an instant-access savings account, but the tax-free prizes and government guarantee make them a strong option for money you hope never to need.
Long-term wealth building (10+ years). If you are saving for retirement, building wealth for the future, or investing for goals more than a decade away, the historical evidence overwhelmingly favours investing. Over any 20-year rolling period, a diversified global equity portfolio has delivered positive returns in the vast majority of cases, and the average returns significantly exceed what premium bonds can offer.
Younger investors. If you are in your 20s, 30s, or even 40s, you have decades of compounding ahead of you. The difference between 3.8% and 7% average returns over 30 years is enormous. Starting early and investing consistently in a low-cost index fund within an ISA is one of the most powerful wealth-building strategies available to ordinary people.
Beating inflation. Premium bonds may or may not beat inflation in any given year — the prize rate fluctuates, and your personal return depends on luck. A diversified equity portfolio has historically beaten inflation by 4-5 percentage points per year on average. Over decades, this difference compounds into dramatically more purchasing power.
Retirement savings. Your pension and long-term retirement savings should almost certainly be invested in equities, not sitting in premium bonds. The compound growth difference over 20-30 years could mean the difference between a comfortable retirement and a constrained one. Premium bonds have their place, but they are not a retirement strategy.
The £50,000 cap matters. Premium bonds have a hard limit of £50,000. Once you reach that ceiling, your capital cannot grow any further (prizes are paid out as cash, not reinvested beyond the cap). An ISA has no limit on total value — only on annual contributions. Over decades, a well-invested ISA can grow to hundreds of thousands of pounds.
Absolutely — and many people do. A sensible balanced approach might look like this:
Emergency fund in premium bonds. Keep 3 to 6 months of expenses (perhaps £5,000 to £15,000) in premium bonds as your safety net. You get government-backed security, tax-free prizes, and access within 3 working days.
Long-term savings in a Stocks & Shares ISA. Direct your regular monthly contributions into a globally diversified index fund within an ISA. This is your wealth-building engine — the money you do not expect to need for 10 or more years.
Surplus cash in premium bonds. If you have already maxed your ISA allowance for the year, premium bonds are an excellent place for additional savings. The tax-free status and government guarantee make them far more attractive than a taxable savings account for most people.
This combined approach gives you the security of premium bonds where you need it, with the growth potential of investing where time is on your side. There is no rule that says you must choose one or the other — the smartest financial plans use different tools for different purposes.
Compare premium bonds vs investing with your own numbers using our free compound interest calculator.
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