Millions of low-income households face a steep rise in their council tax bills because of benefit changes that will take effect from April.
Researchers have warned that a variation in rates of council tax support could undermine the Government's new universal credit, which is meant to simplify the welfare system and ensure it always makes financial sense to take a job.
The axeing of council tax benefit has major implications for universal credit, which is supposed to be all about simplifying welfare and giving people a stronger incentive to work.
"These changes undermine both goals. There will now be a highly-complex and confusing patchwork of local support while the low-paid will keep even less of an extra pound in earnings than the Government has claimed."
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More than 100 people claiming to represent working people across Britain have signed a letter backing Labour in the general election.