Crossroads Care Waveney is to become part of the Papworth Trust, the disability charities have announced.
The Papworth Trust, which employs about 550 staff and has an annual turnover of £20m, will incorporate Crossroads Care Waveney, which has about 40 staff and an annual income of £542,000 in 2010/11.
The new organisation will continue under the Papworth Trust’s name and will work with more than 20,000 people across the east region of England. The organisations hope to complete the merger by the end of the summer.
A Papworth Trust spokesman said the merger, which came about after Crossroads Care Waveney approached the trust, would have an "absolutely minimal" impact on staff numbers.
He said that although the merger had not yet been formalised, Adrian Bagg, chief executive of the Papworth Trust, was expected to become chief executive of the new organisation.
In a statement, Bagg said: "Both Crossroads Care Waveney and the Papworth Trust offer great services. By working together we will offer even more essential support."
Pat Cruse, care manager at Crossroads Care Waveney, said the merger was part of the charity's long-term strategy. She said: "This is what we wanted to do to ensure our provision for the future for our staff and clients."