Girl Scout troops are funded by a share of money earned through council-sponsored product program activities (such as the Girl Scout cookie program), troop money-earning activities (council-approved, of course), and any dues your troop may charge. The girls should always make decisions together on how to spend their funds. All troop money legally belongs to the council to be used by the troop to pay for their Girl Scout activities.
For all the information on establishing troop finances and the policies around it, go to Managing Troop Finances(PDF)