A bill to exempt carers from paying hospital car parking charges will be debated in the House of Commons later.
The level of charges varies between hospital NHS trusts, but the average cost in England is £39 per week and in London it can be about £130 per week.
Labour MP Julie Cooper, who introduced the bill, says the charges are an "unfair burden" on carers.
She says she has cross-party support, but the government has not yet said whether it will back it.
The exemption would apply to NHS hospitals, walk-in centres, GP practices and private hospitals.
'Emotional impact'
The bill has reached its second reading in Parliament.
"Carers have told us that the emotional and financial impact of hospital parking charges seriously undermines their ability to continue caring well for their loved ones and themselves," Ms Cooper said.
"This could be catastrophic for the NHS which, without carers, wouldn't survive.
"The cost of providing carers with free hospital parking in England is negligible when compared with these potential consequences."
The bill would place a duty on health authorities to exempt carers who are in receipt of, or have an underlying entitlement for, Carer's Allowance and those who have been certified by a clinician as providing, or intending to provide, substantial care on a regular basis.
Hospital parking policies are set by individual NHS trusts in England.
Department of Health guidelines on hospital car parking charges suggest concessions should be available for carers with relatives who are gravely ill or who have an extended stay in hospital.
They also say concessions should be offered to people with disabilities and NHS staff whose shift patterns meant they could not use public transport.
Hospital parking charges in Scotland and Wales were abolished in 2008. They have also been axed in most hospitals in Northern Ireland and for those that remain, patients with many long-term conditions are exempt.
Three car parks in Scotland, operated under Private Finance Initiative contracts, still have charges and four hospitals in Wales continue to charge, but have been told to abolish these once contracts with private parking firms end.
Are you a carer affected by the issues raised in this story? You can share your comments and experience by emailing haveyoursay@bbc.co.uk.
http://www.bbc.co.uk/news/uk-politics-34674272