Payment. Where a District Director has made a determination of income tax under paragraph (b) of this section or of section 4955 excise tax, notwithstanding any other provision of law, any tax will become immediately due and payable. The taxpayer is required to pay the amount of the assessment within 10 days after the District Director sends the notice and demand for immediate payment regardless of the filing of an administrative appeal or of a court petition. Regardless of filing an administrative appeal or of petitioning a court, enforced collection action may proceed after the 10-day payment period unless the taxpayer posts the bond described in section 6863. For purposes of collection procedures such as section 6331 (regarding levy), assessments under the authority of paragraph (a) of this section do not constitute situations in which the collection of such tax is in jeopardy and, therefore, do not suspend normal collection procedures.