Hi premium bonds work a little bit like interest rates.
the NS&I bank set an interest rate say of 1.2% (not sure what they’re using right now). They then apply that to the number of bonds held by people. £1 invested is one bond and one chance of winning. There are around 21 million bonds. So £21m pounds which they apply 1.2% to. This equates to the total prize money per month. They then decide how many £1m winners (I think 3 each month) and then the rest of the prizes. There are a lot of £25 win chances for instance- 1000s
so the theory is with “average” luck you’ll get back prizes over the year equivalent to 1.2%.
but here’s the thing…the more you invest the more chances you have. So if you invest £25 (which I think is minimum) you have 25 in 21 million chance of winning a big prize (well actually slightly better if there are 3million pundits prizes), but if you have invested the maximum £40000 you have 40,000 chances in 21 million. So the more bonds you hold the more chance 1 of your bonds will hit a prize each month.
I track the equivalent interest rate I earn with my winning each year. I am pretty spot on average luck in terms of hitting that “interest rate”. But it is almost entirely made up of £25 prizes - some months I get one prize, some months I might get 3 prizes, etc. ok, I may win a bigger prize one day- but the odds even with a hefty amount invested are against me
it is all tax free so that’s why I use it. I could get better interest rate elsewhere but I’d pay tax on it. I could put it into a cash ISA - that’d be tax free but interest rates in cash ISAs have been lower than premium bond equivalent for last few years. I also use my ISAs for stocks and share investments. But I am pensioner and at my limit for tax free interest allowance.
If you’re not and well below that allowance, put it into easy access cash and chase down interest rates by moving it often as they are rising literally each month currently. Don’t be loyal to a single bank- move to highest rates frequently. However, if you are savings longer term then only way to try and beat inflation just now is stocks and shares. But you need to be prepared to invest 7-10years.
you can, unlike stokes and share, buy and sell premium bonds easily without cost. But be aware you’ll only be entered for the draw once you’ve had your money invested for a full calander month . So buy as close as possible to the end of the proceeding month. If you buy bonds say on the 3rd of the month it’ll be nearly 8 weeks before you are entered into the draw.