26 CFR § 20.2056(d)-2 - Marital deduction; effect of disclaimers of post-December 31, 1976 transfers.
(a) Disclaimer by a surviving spouse. If a surviving spouse disclaims an interest in property passing to such spouse from the decedent, which interest was created in a transfer made after December 31, 1976, the effectiveness of the disclaimer will be determined by section 2518 and the corresponding regulations. For rules relating to when the transfer creating the interest occurs, see § 25.2518–2(c)(3) and (c)(4) of this chapter. If a qualified disclaimer is determined to have been made by the surviving spouse, the property interest disclaimed is treated as if such interest had never been transferred to the surviving spouse.
(b) Disclaimer by a person other than a surviving spouse. If an interest in property passes from a decedent to a person other than the surviving spouse, and the interest is created in a transfer made after December 31, 1976, and—
(1) The person other than the surviving spouse makes a qualified disclaimer with respect to such interest; and
(2) The surviving spouse is entitled to such interest in property as a result of such disclaimer, the disclaimed interest is treated as passing directly from the decedent to the surviving spouse. For rules relating to when the transfer creating the interest occurs, see § 25.2518–2(c)(3) and (c)(4) of this chapter.
(c) Effective date. The first and second sentences of paragraphs (a) and (b) of this section are applicable for transfers creating the interest to be disclaimed made on or after December 31, 1997.