Marks & Spencer and Sainsbury’s are expected to face a combined £200m hit to their tax bills after Rachel Reeves Budget.
The two retailers could be forced to increase their prices after the Chancellor unveiled sweeping changes to employers’ national insurance.
Marks & Spencer are set to unveil their half-year earnings on Wednesday, and J Sainsbury will release their interim results the following day.
Industry sources said the pressure on pricing would be “intense” given the thin margins on which the big supermarkets already operate.
“Food price increases from next April are inevitable,” said one.