How Premium Bonds work

Premium Bonds, issued by NS&I, don't pay interest in the traditional sense. Instead, each £1 bond you hold is entered into a monthly prize draw, with tax-free prizes ranging from £25 up to £1 million. The "prize fund rate" — roughly equivalent to an average return if you held the typical luck — is often quoted, but any individual holder's actual return depends entirely on chance and can be zero in any given month, or well above average in a lucky one.

Minimum and maximum holdings

You can hold Premium Bonds from £25 up to a maximum per person, and your original capital is never at risk since it's 100% backed by HM Treasury — this is capital preservation with a lottery-style return, not a growth investment.

Who they tend to suit

  • People who want complete capital security with a chance of a tax-free windfall, rather than a guaranteed return.
  • Additional-rate taxpayers, since prizes are entirely tax-free regardless of your other income, unlike ordinary savings interest.
  • Those who find the "game" element appealing as a way to make saving more engaging.

Who they tend to suit less well

Anyone who needs a predictable, reliable return each month or year is generally better served by a standard savings account or Cash ISA, since Premium Bond returns are inherently unpredictable and, for smaller holdings, there's a meaningful chance of winning nothing at all over long periods, even though the "average" statistical return sounds reasonable.

The maths in plain terms

With a smaller holding, the odds of winning any single prize in a given month are relatively low, meaning your actual experienced return can differ substantially from the quoted average rate — sometimes for years at a time, in either direction. Larger holdings smooth this out somewhat, since more individual £1 bonds means more chances, converging closer to the average over time.

Key takeaways

  • Premium Bonds offer a monthly prize draw instead of guaranteed interest, with capital 100% protected by HM Treasury.
  • Actual returns vary by luck and can be zero or well above the quoted average rate.
  • Prizes are entirely tax-free, appealing particularly to higher and additional-rate taxpayers.
  • Smaller holdings see more variation in actual return; larger holdings track closer to the average.