The amount of cash deposited by businesses using Post Office branches plunged by 40% in January compared with a year earlier.
Business cash deposits were down by 40.7% to total £582 million in January, the Post Office said.
This compared with £981 million in January 2020, before any UK coronavirus lockdowns.
Personal cash deposits in January totalled £931.6 million.
This was £47 million lower than in December, which tends to be the busiest month for deposits, although it was still up by 4.6% compared with January 2020, when personal deposits totalled £890.3 million.
The Post Office has an agreement with banks and building societies which means that 99% of UK bank customers can access their accounts at a Post Office branch. It has around 11,500 sites across the UK.
Personal cash withdrawals totalled £463 million last month, compared with £611 million in January 2020.
It marked the lowest amount withdrawn at Post Office’s counters since May 2020 (£450 million).
Martin Kearsley, director of banking at the Post Office, said: “An over 40% fall in business cash deposits compared with same period last year continues to highlight the impact the Covid-19 lockdown is having on the UK’s small businesses and the self-employed who have traditionally relied on Post Offices to deposit their takings.
“It’s encouraging that personal cash deposits continue to rise. We have remained open during this lockdown to support our local communities. 99% of our branches are open, many late into the evenings and at the weekend, providing a critical cash service for personal and business customers.”