the Secretary shall immediately make a determination of any income tax payable by such organization for the current or immediately preceding taxable year, or both, and shall immediately make a determination of any tax payable under section 4955 by such organization or any manager thereof with respect to political expenditures during the current or preceding taxable year, or both. Notwithstanding any other provision of law, any such tax shall become immediately due and payable. The Secretary shall immediately assess the amount of tax so determined (together with all interest, additional amounts, and additions to the tax provided by law) for the current year or the preceding taxable year, or both, and shall cause notice of such determination and assessment to be given to the organization or any manager thereof, as the case may be, together with a demand for immediate payment of such tax.