The total amount of unclaimed income-related benefits and social tariffs is now £18.7bn a year, a new study has found.
The report from think tank Policy in Practice estimates that £7.5bn of Universal Credit is unclaimed by 1.2 million eligible households.
The report, entitled Missing out: £19bn of support goes unclaimed each year, also found that £2.9bn of Council Tax Support is unclaimed by over 2.7 million eligible households each year.
The think tank says that benefits go unclaimed because of administrative complexity and a lack of awareness among potential claimants that they are eligible for support.
It also highlighted the stigma associated with claiming benefits and the increasing fragmentation of support.
As well as unclaimed Universal Credit and Council Tax Support, the report estimated there was £2bn in unclaimed Carers Allowance and £1.75bn in Pension Credit. Child Benefit (£1.13bn) and Housing Benefit (pension age) (£929m) were also cited.
The think tank advises councils to identify eligible residents using data analytics and contact them to inform them of the benefits they are missing out on.
