The National Council for Voluntary Organisations is proposing to cut 17 out of 121 full-time equivalent posts as part of an organisational restructure.
The charity said it was making cuts because a number of duplicate roles now existed after its merger with Volunteering England last month, and because it had lost funding from the Office for Civil Society.
Thirty members of staff have been advised that they are at risk of redundancy because of the restructure, although it is not yet clear which jobs will go.
Proposals for the restructure, which are subject to a month-long consultation with staff and union representatives, include creating a department of volunteering and development, which will support volunteer centres, volunteer managers and volunteering organisations, work on quality standards in volunteering and Volunteers’ Week, and administer the Big Assist programme, which helps strengthen voluntary sector infrastructure.
Volunteering policy and research will become part of NCVO’s public policy department remit.
The NCVO will also look to improve online services and online information for members.
Sir Stuart Etherington, chief executive of the NCVO, said: "Inevitably, in merging two organisations there will be some duplication of roles, and I am very sorry that we will lose some excellent staff members.
"We are proposing a structure that will position NCVO to be a strong voice, independent of core government funding. These changes will equip us to better serve our 10,000 members and to work on behalf of all charities and volunteers."