The new lower rate will only apply to kegs 40 litres and over.
However, Carshalton and Wallington Tory MP Elliot Colburn says many small breweries use 20 or 30 litre kegs, and rely on community wet-led pubs for their business.
Rishi Sunak’s policy has been criticised after posing with kegs too small to be eligible for the relief.
The Treasury says they’re consulting industry to ensure it benefits pubs rather than supermarkets, which can sell smaller kegs.