Consumers should be given a guarantee that they will have access to cash, as they do with water, electricity and the post, a charity says.
Some 2.4 million people aged 65 and over rely on cash in their daily lives, Age UK said.
The charity warned that many would face being excluded from society if they could not get hold of notes and coins.
Various trials are taking place across the UK to help those who require cash, including testing new banking hubs.
Cash use in purchases fell sharply during the pandemic, as lockdowns reduced the options for spending. This accelerated a trend of falling use of notes and coins in transactions.
Some people turned to digital channels for their banking for the first time, if they were unable to leave home.