The Union Ħaddiema Magħqudin has registered an industrial dispute with the Foundation for Social Welfare Services.
The foundation, made up of Appoġġ, Sapport, Sedqa and Adult Training Centres, failed to award a number of allowances and arrears to full-time and part-time care and support workers, the union claimed.
This, it said, is in breach of the collective agreement.
In the coming days the union will meet the workers at its headquarters in Floriana to decide on further action.
When contacted, the Foundation for Social Welfare Services' CEO, Joe Gerada, preferred not to comment apart from saying that meetings between management and the union were taking place.