(a) General rule.--Except as provided in subsection (b) and subject to section 2803 (relating to judicial proceeding), a will, trust or other dispositive instrument of a decedent who dies after December 31, 2009, and before January 1, 2011, that contains a formula clause shall be rebuttably presumed to be interpreted pursuant to the Federal estate tax and generation-skipping transfer tax laws applicable to estates of decedents dying on December 31, 2009.
(b) Exception.--
(1) Subsection (a) shall not apply with respect to a will, trust or other dispositive instrument that:
(i) is executed or amended after December 31, 2009; or
(ii) manifests an intent that a contrary rule shall apply if the decedent dies on a date on which there is no applicable Federal estate tax or generation-skipping transfer tax in effect.
(2) If the Federal estate tax or generation-skipping transfer tax applies to an estate of a decedent dying or generation-skipping transfer occurring before January 1, 2011, then with respect to each such Federal tax, the initial reference to January 1, 2011, in this section shall refer instead to the first date after December 31, 2009, on which such tax applies to decedents' estates or generation-skipping transfers.