Official inflation figures may marginally drop in March as the Office for National Statistics greatly expands its dataset and takes loyalty pricing and multibuy discounts into account for the first time.
From next month, the ONS will replace 25,000 monthly price points, recorded in store by price collectors, with 300 million price points from over a billion sold products. The information is taken directly from supermarkets’ till data, representing half of grocery sales.
The expanded dataset will feed into the consumer price indices (CPI and CPIH), retail price index (RPI) and household cost indices (HCI) publications from March 2026.
Mike Hardie, deputy director for prices transformation, described the move as a “step change in our measurement of inflation”.
“Now, rather than assuming the change in the price of one type of apple in a supermarket reflects all apples, for the shops supplying us with scanner data, we will be able to see how the price of every apple changes as well as knowing exactly how much of each type of apple is bought, so can adjust the figures for changing buying habits,” he said.
“It will also allow us to better capture the impact of a wider range of promotions, such as store discount cards, on average price inflation. This means the price charged at the till, not the price shown on the shelf, will feed into our inflation statistics.”
The ONS has developed and trialled using scanner data for years. Doing so would have lowered the annual CPI figure by 0.03 percentage points on average between January 2019 and June 2025, it said, but that the impact of scanner data was inconsistent and would have both increased and decreased inflation in different time periods.
Groceries make up 12% to 15% of the baskets used to measure inflation, which the ONS said would moderate the impact of using scanner data. It will also continue in-store and online price collection for the remaining half of the groceries market.
UK inflation rose to 3.4% in December, up from 3.2% the previous month.
March’s inflation numbers will include two further improvements. The ONS will collect hotel and video game prices for an extra day each month to reduce volatility from big event and new releases.
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