If tax is imposed under subsection (a) on the lobbying expenditures of any organization,
there is hereby imposed on the agreement of any organization manager to the making
of any such expenditures, knowing that such expenditures are likely to result in
the organization not being described in section 501(c)(3)
, a tax equal to 5 percent of the amount of such
expenditures, unless such agreement is not willful and is due to
reasonable cause. The tax imposed by this subsection shall be paid by any manager
who agreed to the making of the expenditures.