Planned government changes to council tax benefits will leave people on low and middle incomes worse off and wipe out the benefits of the rise in personal allowances, trade union Unison has claimed.
General secretary of the union Dave Prentis has written to David Cameron and Nick Clegg urging them to reconsider replacing the national system of council tax benefits with what the body calls a "postcode lottery" of local schemes.
Mr Prentis said: "We hear a lot from Cameron and Clegg about helping low paid workers, but actions speak louder than words."
If true, Unison's claims could leave many lower-income people who have debts struggling even more to pay them when their new council tax bills start to arrive.
Consumers have already been getting worse off due to having their incomes squeezed by inflation.
A study by MGM Advantage published this month concluded the typical household needs an extra £897.73 a year to maintain the same standard of living it had a year ago.
By contrasts, many people will have seen their incomes stagnate due to low pay rises, a pay freeze or even a fall in remuneration due to reduced working hours.
By James Francis