Unison is to ballot care staff at housing provider Family Mosaic on whether to strike over proposals to slash pay and increase working hours.
Staff on the organisation's care and supported housing team, which helps vulnerable adults in London and Essex to live in the community and integrate into society, are among those facing average pay cuts of 8.5%, according to Unison.
Family Mosaic said it had suffered a "significant reduction in funding" to its care services, resulting in the need to cut staff pay. But Unison claimed the proposals would push some frontline staff into poverty.
"Apart from legal action that we will vigorously pursue with our members we have no choice but to go into dispute," said Unison's Essex regional organiser, Nick Bradley.
"We are now asking our members whether they would support strike action to defend their terms and conditions."
A spokesperson for Family Mosaic responded: "The proposals we have put to staff are essential to deal with the significant reductions to the funding we are receiving to run our care and support services.
"Under current proposals no one is losing their job and we are maintaining quality services and still offering a competitive employment package to all our staff.
"All our salaries reflect the current market and will continue to do so, it is regrettable that some staff will have pay cuts but we are phasing them in slowly; more than 50 staff will get pay rises as a result of the proposals and many are getting increased annual leave."
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Housing association cuts branded appalling by union