The charity will label council tax a 'major headache for millions' and highlight the fact that council tax benefit is 'the most unclaimed benefit of all' in research published today (8 April).
The study shows that up to 1.8 million pensioners are missing out on around £900m in council tax benefit.
The statistics will kick off the charity's annual awareness campaign around Your Rights Week, which runs from 8-15 April.
The campaign aims to raise awareness of the level of poverty among older people and to educate the elderly about the benefits to which they are entitled. 'An awful lot of older people are home owners,' said Age Concern senior media officer Helen Wanless. 'Many don't realise they're entitled to council tax benefit because they live in valuable homes - despite having a low fixed income.'
It will target financial and retirement press.