The Premium Bonds prize checker will update tomorrow, August 2.NS&I warns all Premium Bonds customers to act before end of SaturdayNS&I warns all Premium Bonds customers to act before end of Saturday

National Savings and Investments has urged Premium Bonds holders to check their accounts before the close of play on Saturday – as the August winners were announced. The Premium Bonds prize checker will update tomorrow, August 2.

Two Premium Bonds holders have become millionaires in the latest prize draw for August, each taking home £1 million tax-free. The first winner is from Central Bedfordshire and held £7,000 in Premium Bonds. Their winning number, 148YD123622, was purchased in December 2008.

The second winner, based overseas, had £50,000 invested. Their winning bond, 205XQ030808, was bought in May 2013. Both prizes are entirely tax-free and were awarded through NS&I’s monthly draw.

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NS&I, which is backed by the Treasury, split the prizes into three value bands – higher, medium and lower – and allocate a percentage share of the monthly prize fund to each band.

It pays out two £1 million jackpots each month and will then divide the balance of the prize fund share allocated to the higher value band equally among the remaining prize values.

“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,” NS&I says.

Or when there’s a balance that’s at least half of the prize value, it will award an additional prize of £100,000. It does this by taking the shortfall from the share for the £50,000 prizes.

It then calculates 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.

And it says: “In the unlikely event of a shortfall in the total number of prizes, we may increase the share allocated to the lower value band and reduce the shares allocated to the higher and medium value bands.

“Any surplus will be carried forward to the prize fund for the following month.”

NS&I has 24 million customers who can all check their accounts via the website and online checker as well as the app.