Premium Bond holders have been issued a warning by NS&I over a deadline that could stop them from winning.

NS&I shared the warning after a customer reached out to the company on X, formerly Twitter, to ask: "If I was to buy some Premium Bonds, what's the latest I can buy to qualify for the end of the month?"

The brand quickly responded: "Premium Bonds need to be held for a full calendar month before being eligible for a draw.

"The next available draw for newly purchased Bonds is October - to be eligible for the October draw, the latest you can purchase the Bonds to do so would be 31 August."

Answering more questions and concerns to Premium Bond holders, NS&I explained to one customer that "interest is not earned on Premium Bonds, so the value of the Bonds will remain the same."

How do Premium Bonds prizes work? 

Premium Bonds prizes are split into three bands: higher, medium and lower value.

They are allocated based on each band's percentage share of the monthly prize fund.

Higher band

There are two £1 million jackpots each month.

NS&I divide the balance of the prize fund share allocated to the higher value band equally among the remaining prize values.

Explaining how the higher band works, NS&I writes on its website: "First we work out the number of £100,000 prizes.

"When there is a balance that’s less than half of that prize value, we carry it over to the share for the £50,000 prizes. Or when there’s a balance that’s at least half of the prize value, we award an additional prize of £100,000. We do this by taking the shortfall from the share for the £50,000 prizes.

"We then calculate the numbers of other prizes in this value band in the same way, from highest value to lowest value.

"When calculating the number of £5,000 prizes, any surplus or shortfall is added to or taken from the medium value band."

Medium band

NS&I calculates the number of prizes within the medium band so that there is one £1,000 prize for every three £500 prizes.

If there is any leftover, the surplus is added to the share allocated to the lower value band.


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Lower band

The number of lower value prizes is so that there’s an equal number of £100 and £50 prizes, the Ns&I has explained.

It added: "The total number of prizes of all values (including £25 prizes) is equal to the number of eligible £1 Bond units divided by the odds".