The financial structure is designed to make the headquarters financially lean (unattractive). This makes the centers financially independent units as they retain their inflows.
The national office develops a zero-based budget every year and this budget is funded by the unit centers without any room for excess funds at the H/Q.
With this arrangement, it is assumed that each center will be financially independent enough to fund growth plans. In case they are not, there are structures in place to accommodate such needs.