Election

An election under this subsection shall be made at such time and in such manner as the Secretary shall by regulations prescribe. Such an election, once made, shall be irrevocable.

If an election is made under this subsection with respect to any additional estate tax imposed under section 2032A(c)(1), for purposes of section 6601 (relating to interest on underpayments), the last date prescribed for payment of such tax shall be deemed to be the last date prescribed for payment of the tax imposed by section 2001 with respect to the estate of the decedent (as determined for purposes of section 6601).