Scotland's leading pensioners' groups have joined forces to urge politicians to come up with an alternative to the current council tax system.
Charities claim pensioners are being discriminated against
Help the Aged has launched a petition backed by 14 other organisations, including Age Concern Scotland and the Scottish Pensioners Forum.
It claims that senior citizens are being unfairly discriminated against.
The groups want an independent expert body to examine the issue as part of a review of local government finance.
The petition says: "Its remit must specifically consider the fairness and administration of the existing council tax and water charging systems and the viability of replacement with other more equitable revenue raising measures."
Pensioners' groups claim the elderly could pay up to a quarter of their income in tax.
The Convention of Scottish Local Authorities (Cosla) said the average increase in bills set across Scotland earlier this month was 4.4%.
But campaigners have called on the Scottish Executive to think again about how local authorities are financed.
Ministers are planning an independent review of local taxation and are discussing the final details of its remit with Cosla.
Help the Aged said it was afraid this would not look at the bigger picture.
It insists it has already won wide support for the campaign to have a root and branch reform of council tax.
The petition calling for change will be handed to the Scottish Parliament.
Help the Aged spokesman Lindsay Scott said: "The petition calls on the executive and Cosla to take a long, hard look at the current method of raising funds and find something more equitable.
"Including water rates, council tax has gone up by 91% over the last decade while the state pension has gone up by 38%. And every year the gap widens.
"Every year council tax rises by above the rate of inflation while the pension does not - it goes up in line with cost of living and pensioners simply
cannot afford it."