There are almost 30,000 individuals and families on council housing waiting lists across Suffolk and the north of Essex, new figures reveal.

The statistic is being highlighted by ministers to explain why controversial changes to the housing benefit system are needed.

Reforms, branded the “bedroom tax” by Labour, will see claimants deemed to have too much living space receiving less money from April.

Those with one unused bedroom in their council or housing association home will lose 14%of their payment, while those with two unused bedrooms will lose 25%. Critics have said the changes will see disabled and other vulnerable groups losing money unfairly.

But ministers argue they are needed because some people live in properties with unused rooms while others are stuck on waiting lists or crammed into homes too small for their family.

Work and Pensions Secretary Iain Duncan Smith said figures from his department showed there were also 22,000 households across the East of England living in overcrowded homes.

He said: “There’s nothing fair about making families wait and wait for a house that is big enough, while other households on benefits are allowed to live in homes that are too big for their needs, at no extra cost.”

In Babergh in 2012 there were 1,748 on the waiting list, in Forest Heath there were 1,424, in Ipswich – 4,713, in Mid Suffolk – 1,230, in St Edmundsbury – 2,131, in Suffolk Coastal – 2,553, in Waveney – 2,279, in Braintree – 3,062, in Colchester – 4,877 and in Tendring – 3,376.

The secretary of state continued: “Many working families in Suffolk cannot afford the luxury of having spare bedrooms, and the government cannot afford to pay for bedrooms that are not being used.

“That’s why from April housing benefit claimants living in social housing with spare bedrooms will be expected to make a contribution towards the rent for those spare rooms.”

He characterised the changes as removing a “spare room subsidy” that he said claimants in “oversized” housing had effectively been receiving.

Under the plans anyone living in such a home will have to undergo an assessment with their council to see if they qualify for an exemption.

The new policy will allow one bedroom for each person or couple living as part of a household. Two children aged nine or under would be expected to share a room.

Two youngsters between age nine and 15 would also be expected to share, though only with a child of the same gender.

Ministers say the change will only apply to working age claimants. Assessors may also give an exemption where there is a spare room for a non-resident carer who stays over.

Meanwhile officials at Mr Duncan Smith’s department informed our reporter that councils will have discretion to offer exemptions outside those outlined by the Whitehall department where they see fit.

According to figures from the National Housing Federation, representing housing associations, some 50,000 people across the East could be affected.

Across Suffolk and north Essex 9,105 people will have to undergo an assessment, including 5,736 with a disability.