There is more than £50million out there in unclaimed Premium Bonds prizes - but more than three-quarters of customers have never won anything.
Premium Bonds are issued by National Savings & Investments (NS&I) and are the most popular type of savings in the UK.
NS&I offers payouts of between £25 and £1million every month, but many of these prizes are not claimed.
This can happen if the original owner of the bond has died and NS&I has not been notified, or if you move house and fail to notify the savings institution.
Other common cases include where the person was given Premium Bonds as a child - which they later forgot about.
Have you won big on Premium Bonds and want to share your story? Let us know: mirror.money.saving@mirror.co.uk
Research by financial firm Quilter has found that 1.7million Premium Bonds prizes have gone unclaimed since April 2007, worth £50.8million.
An unclaimed prize is defined as not paid to customer/cashed within 18 months of draw.
Quilter also found that 74% of Premium Bonds savers have never won a prize.
According to a Freedom of Information (FOI) request to NS&I nearly 15.7million of the 21.1million Premium Bond savers have never won a prize since records began in 2007.
Quilter financial adviser Edmund Hastie said: "These figures go to show that not all savings products are made equally.
"Premium bonds have for a long time been a firm favourite among parents and grandparents as a way of cascading wealth down to children and grandchildren and setting them up for adulthood.
"But as these figures illustrate the return can be non-existent unless you have very large holdings that make it easier to win a prize."
An NS&I spokesperson said: "Premium Bonds are 100% backed by HM Treasury and the prizes are tax-free – every £1 bond has an equal chance of winning any prize, and whilst customers with higher holdings have more chances to win prizes, we have had customers with relatively small sums in Premium Bonds win significant prizes, i.e. in August 2021 a winner from Devon scooped the £1 million jackpot with a holding of £1,001.
"We recently increased the prize fund rate from 1.00% to 1.40% and the odds of each £1 Premium Bond number winning a prize also improved.
"Since June, the number of prizes paid out each month has increased from circa 3.4 million to circa 4.8 million – the highest number of prizes in any monthly Premium Bonds prize draws to date."
How to track down Premium Bonds prizes
You can download a list of all unclaimed bond numbers here.
For recent prizes, you can check if you've missed out by visiting NS&I and using its online prize checker.
If you have lost the details of your account, want to register updated details, or want to notify NS&I of a bond-holder's death, you can telephone NS&I on 08085 007 007.
Website My Lost Account can also tell you if you hold any Premium Bonds which you may not have been aware of.
How do NS&I Premium Bonds work?
Premium Bonds work a bit like a lottery.
Each bond costs £1, and functions like a lottery ticket.
Every bond is entered into a monthly prize draw where you can win between £25 and £1million tax free.
Each bond gives a separate chance to win.
Your chance of winning is completely down to chance - and you may not win anything at all.
Whenever you want to you can get all your money back from NS&I, though it may take a few days.
The minimum amount you can have invested in Premium Bonds is £25, and the maximum is £50,000.