The so-called “bedroom tax” will be scrapped on “day one” of a Labour government, Ed Miliband will claim.
The Labour leader is travelling across England, Scotland and Wales on Friday to tell voters that ending the measure would be his first act in power.
The party says it would also bring in a “hardship fund” so that during the months it would take for the legislation to be changed in Parliament, people affected would be compensated with money distributed through local authorities.
This compensation would apply to the first day of a Labour government.
Mr Miliband will say: “We’ll get to work immediately to ensure that families no longer lose out.
“So on day one of a Labour government, we free families from the burden of the bedroom tax.”
Since April 2013, tenants in council and social housing who are deemed to have surplus bedrooms for their needs have seen their housing benefit cut by up to 25% – a key plank in the Government’s efforts to reduce growth in welfare spending.
The coalition has argued that the measure helps with the housing crisis – while saving on revenue if people do not want to move.
But visiting Cardiff, Glasgow and Bristol, the Labour leader will describe the spare-room subsidy as “indefensible and cruel”.
Mr Miliband says he will pay for the move by ending the “shares for rights” scheme and changing tax laws for hedge funds.
Under the last government, a Private Member’s Bill backed by Labour and the Liberal Democrats sought to change the measure so that people who could not be found a smaller home would be exempt from the cuts, as well as disabled people who need a spare bedroom or who have adapted homes.