Most of the Assembly's funding is provided by contributions from the parliaments or governments of member nations. National contributions are determined according to the same budget key used for the NATO civil budget. The Assembly also receives a financial contribution from NATO.

During the past 25 years special contributions have been made by the United States Agency for International Development, Geneva Centre for Security Sector Governance, the Government of Switzerland, Norway, Luxembourg, Denmark and NATO to support the Assembly's Rose-Roth programme.

The annual budget is currently about € 4,7 million. This is used to cover the International Secretariat's operating costs. National delegations are responsible for funding the participation of their members in Assembly activities.

The Assembly's Treasurer is responsible for drafting the Assembly's budget which is submitted to the Standing Committee, and the full Assembly for consideration and adoption.