For purposes of this subtitle, if both the executor (if any) of an estate and the trustee of a qualified revocable trust elect the treatment provided in this section, such trust shall be treated and taxed as part of such estate (and not as a separate trust) for all taxable years of the estate ending after the date of the decedent’s death and before the applicable date.
26 U.S. Code § 645. Certain revocable trusts treated as part of estate
(a) General rule
(b) DefinitionsFor purposes of subsection (a)—
(1) Qualified revocable trust
(2) Applicable dateThe term “applicable date” means—