Businesses and individuals have returned to post offices to deposit cash built up over lockdown.
The reopening of small firms has also led to cash deposits increasing in July, reaching more than double April levels.
Withdrawals have seen a slower rebound as people have turned, in part, to contactless payments.
The figures come after High Street bank TSB said it was widening the roles of cashiers in its branches.
Lockdown cash use
The use of cash plummeted during lockdown with most shops, pubs and restaurants shut.
The limit for the use of contactless debit and credit cards was also raised from £30 to £45 in April to aid social distancing in stores that remained open.
Some businesses, however, still accumulated cash and individuals took fewer trips out to deal with their finances.
Post offices remained open, but new research has found that cash deposits rose by 27% in July compared with June.
Business cash deposits 63% higher in July than in June, and have reached pre-Covid levels, according to the inaugural Post Office Cash Tracker.
Cash deposits by personal customers were higher than a year ago. The Post Office suggested some were now using its counters as an alternative to bank branches, many of which have their own restrictions. Banks have an agreement with the Post Office to allow their customers to deposit and withdraw money from bank accounts.
Natalie Ceeney, who authored a major report about the future of cash, said that the Post Office had a vital role to play in supplying cash to communities.
"We know from experience in Sweden that supporting the cash infrastructure is not only about access to cash, but also the ability to deposit it too, especially for small businesses," she said.
TSB cashiers 'upskilled'
The figures come as TSB said 929 of its staff were being offered extra training to take on roles beyond cashier positions. The alternative is voluntary redundancy.
Image copyright Getty ImagesThe bank, which is in the process of closing branches across the UK, said staff would be able to help people open accounts and use other services.
"The way customers use their banks is changing and Covid-19 has significantly accelerated the use of digital services," a TSB spokesman said.
"When customers visit our branches, their needs tend to be more complex and we need a fully multiskilled and flexible workforce to meet them. This is why we are offering some branch colleagues the opportunity to upskill to take on broader customer service roles or take voluntary redundancy."
Unions have expressed concerns that coronavirus has been used as an excuse to water down dedicated roles or cut jobs.