Up to two million pensioners are failing to claim a council tax benefit that they are entitled to, a charity has warned.
Old people are losing most by not claiming benefits
Age Concern said that claiming the benefit could help some pensioners cut their bills by more than £500 a year.
More than of £1.1bn goes unclaimed in council tax benefit for older people each year, Age Concern said.
Many pensioners are reluctant to claim because of lack of knowledge and stigma, the charity added.
"It's really worrying that so many older people are still not receiving the financial help that they are entitled to," Gordon Lishman, Age Concern's director-general, said.
"Millions of pensioners across the UK are struggling to manage on a really low fixed income and are increasingly anxious about paying their bills," he added.
Age Concern's warning coincides with the launch of Your Rights Week, its annual campaign to encourage older people to claim all the money that is available to them.