On the first anniversary of the controversial cutback, which is described by ministers as the removal of a "spare room subsidy", Iain Duncan Smith's department released figures showing that almost half a million households were having cash deducted from their benefits.
Under the new rules, social housing tenants deemed to have one more bedroom than they need lose 14% of their eligible rent and those with two or more lose 25%.
DWP figures showed that in November 2013, some 498,000 social housing tenants in England, Scotland and Wales were having their benefits reduced under the policy.
This figure was 50,000 down on numbers affected in the first month of the policy's operation, suggesting that tens of thousands of tenants have moved to smaller accommodation.
Changes to housing benefit in the social rented sector are expected to save £490 million in 2013/14 and a total of around £1 billion by the end of 2014/15, equating to more than £1.3 million per day, the DWP said.
Critics said the tax was forcing disadvantaged tenants into rent arrears, putting them at risk of losing their homes.
A recent survey for the National Housing Federation found that 66% of housing association residents hit by the bedroom tax were in arrears and more than one in seven (15%) had received a letter warning them they were at risk of eviction.
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