Trade union GMB said it is "sickening" that nurses, midwives and cleaners in many trusts across the country have had to shell out money to park at their place of work, as it called on ministers to scrap parking charges for workers altogether.
NHS Digital data shows Shrewsbury and Telford Hospital NHS Trust made around £2.2 million through parking charges and penalty fines in the year to March 2020.
Of that, £1.5 million was paid by patients and visitors, while £705,903 was raked in through charging staff to park.
Parking charges were temporarily suspended at the start of the coronavirus pandemic, with the Department of Health and Social Care providing funding to NHS trusts to cover lost revenue.
SaTH says any money raised by car parking charges is reinvested directly into patient care.
A spokesman said: "Parking charges for our staff were suspended near the beginning of the coronavirus pandemic and remain so.
“Members of the public are able to park for up to 20 minutes for free if they are dropping off or collecting patients. Patients receiving dialysis, radiotherapy or chemotherapy, and people visiting hospital for issues connected with bereavement, can park for free.
"Anyone needing to attend hospital regularly can buy a discounted 10-visit ticket which is valid for three months and has no time restrictions or limits; whilst patients on low incomes, who are in receipt of benefits, can also claim back the cost of their parking.”
The data also showed Robert Jones and Agnes Hunt Orthopaedic Hospital, near Oswestry, made £415,187 through parking charges and penalty fines in the year to March 2020.
Of that, £330,751 was paid by patients and visitors, while £84,436 was collected through charging staff to park.
But Mark Brandreth, chief executive of the trust, said it had suspended parking charges for all staff at the start of the pandemic last year and there are "no current plans to re-introduce them".
Across England, NHS trusts raised £289 million from parking charges – nearly a third of which came from staff parking, generating £90 million over the year.
The figures represent the gross income earned by the NHS and do not take into account its own costs for providing car parking.
Workers are losing £2 or more from their pay packet every hour at the most expensive car parks nationally, the data shows.
Trade union GMB said charging NHS staff to park at work is "disgraceful".
Rachel Harrison, the union's national officer, said: "Government cuts have inflicted a heavy toll on the NHS, but trusts should not be clawing that cash back by charging the people we rely on to keep us alive."
The Government announced last year that it would cover the costs of providing free car parking to NHS staff working in hospitals during the coronavirus pandemic. However, it said the scheme would end in all but "certain circumstances" as the pandemic eased over the summer.
Ms Harrison added that it was "sickening" to see workers forced to shell out for parking again as some trusts reintroduced charges for staff.
“Ministers must now support our healthcare heroes by enforcing free hospital staff parking and scrapping plans to reintroduce charges once the pandemic ends," she added.
Patients' rights campaigners the Patients Association said while billing people to park at NHS car parks is a "charge on people who are unwell," it provides much-needed income for trusts at a time when their finances are under pressure.
A spokesman for the Department of Health and Social Care said: "In March, the Government committed to making hospital car parking free for NHS staff for the duration of the pandemic and is providing additional money to NHS trusts to cover the cost of implementing this.
"Any surplus income generated from hospital car parks not used to fund the provision of car parking, such as security and maintenance, must be reinvested into frontline care."
But greater clarity on the overall funding pot for free staff parking is needed, according to NHS Providers, which represents trust leaders.
In a briefing to MPs, the organisation said it is "vital" that trusts receive enough funding to pay for the measure to enable them to maintain services and put money into frontline services.
It added that some trusts had already reinstated charges for workers to ensure there were enough spaces for staff and patients as people avoid public transport during the pandemic.