Housing employees at Greenwich Council in London are being balloted for strike action over the ending of a productivity agreement.
The Unite union says its members face losing £10,000 a year if the long-standing agreement comes to an end.
It is sending voting papers to its 118 housing maintenance members at the council this week in a ballot which will close at the end of the month.
The council wants to end the six-year old productivity scheme from 1 October.
Unite regional officer, Onay Kasab, said: 'The proposed withdrawal of this six-year-old agreement with only the most cursory consultation with Unite will see our hardworking housing staff members losing out to the tune of £10,000 a year.
'To lose this enormous amount is a massive blow to their incomes when the cost of living in London, one of the world’s most expensive cities, is sky-high.
'However, there always seems to be enough cash to pay expensive consultants a thumping £1.5m on the repairs’ service over the last six years.
'If our members vote for strike action, this will seriously hinder and disrupt the council’s housing repair programme, but there is still time for the council to sit down with Unite to have a meaningful dialogue on this issue.'