The IRS also recognizes that “"the two
organizations [a (c)(3) and a (c)(4)] may share
staff, facilities, or other expenses or...conduct
joint activities requiring an allocation of income
and expenses,” but the allocation must be
carefully reviewed to ensure that it is appropriate
and that the resources of the IRC 501(c)(3)
organization are not used to support the political
campaign activity of the IRC 501(c)(4)
organization or its PAC.