A group of charities is calling for an end to a rule which, they say, brings debt and eviction to some young people.
The rule has made it hard for some young people to find a place to live
The charities are targeting the single room rent restriction, which was introduced 10 years ago.
This limits the amount of housing benefit for people under the age of 25 to the average local rent for shared accommodation.
The charities say that 87% of under-25s who claim housing benefit are left with an average shortfall of £35 a week.
This figure was calculated last year by researchers for the Department for Work and Pensions (DWP).
The charities say that the lack of affordable or shared housing in most parts of the country means some young claimants are unable to pay their full rent.
As a result, the charities argue, this "obscure" housing benefit rule brings hardship and homelessness to the under-25s living in private rented accommodation.
"The single room rent restriction has left many young people out of pocket and struggling to pay their rent, plunging them into a cycle of homelessness, unemployment and poverty," said Adam Sampson, chief executive of the charity Shelter.
"After 10 years, it's time for ministers to end this grossly unfair discrimination against young people," he added.
The organisations backing the campaign include Shelter, the YMCA and Citizens Advice, as well as landlords' organisation the British Property Federation.
They argue that the rule particularly hits young people moving out of charitable housing into private rented accommodation.
The charities are calling for the single room rent restriction to be abolished through an amendment to the Welfare Reform Bill.
In the 1998 Budget the government abolished the rule for 25-59 year olds, but kept it for younger people.
The number of people being assessed under this rule has halved in the past seven years.
A Parliamentary answer earlier this year revealed that in 1999 there were 24,790 such assessments, but by 2005 the number had declined to 11,990.