The Greater Manchester Combined Authority (GMCA) is the top-tier administrative body for the local governance of Greater Manchester. The combined authority was established on 1 April 2011 and consists of ten indirectly elected members, each a directly elected councillor from one of the ten metropolitan boroughs that comprise Greater Manchester. The authority derives most of its powers from the Local Government Act 2000 and Local Democracy, Economic Development and Construction Act 2009, and replaced a range of single-purpose joint boards and quangos to provide a formal administrative authority for Greater Manchester for the first time since the abolition of the Greater Manchester County Council in 1986.

Each member has one vote with the chair not possessing a deciding vote, each council nominates one member and one stand-in member in the case of absence. The constituent council may at any time terminate the membership of its nominee, the nominee will also cease to be a member if at any time they should cease to be an elected representative and a new nominee must be selected as soon as possible. The GMCA will elect a Chair and Vice-Chair from amongst its members. All questions arising before the GMCA will be decided by a simple majority vote, and if a vote is tied it is considered to be lost. Several subjects will however require an enhanced majority of seven votes in favour, these are:

• The adoption of the Sustainable Community Strategy (i.e. the Greater Manchester Strategy, the Greater Manchester Housing Strategy and other related strategies)
• The adoption of the Multi-Area Agreement
• The approval of the local economic assessment
• The adoption of the Local Transport Plan and policies contained therein
• The combined authority’s annual budget
• The setting of the transport levy
• Approval of new schemes to be financed by the Greater Manchester Transport Fund
• Borrowing limits, Treasury Management Strategy, the investment strategy and the capital budget
• The acceptance of any proposed delegation of functions and budgets to the GMCA by the Secretary of State
• Such other plans and strategies as are determined by the GMCA

The GMCA meets at the same time as the AGMA Executive Board.