(a) In general. Generally, no marital deduction is allowable if the interest passing to the surviving spouse is a terminable interest as defined in paragraph (b) of § 20.2056(b)(1). However, section 2056(b)(3) provides an exception to this rule so as to allow a deduction if (1) the only condition under which it will terminate is the death of the surviving spouse within 6 months after the decedent's death, or her death as a result of a common disaster which also resulted in the decedent's death, and (2) the condition does not in fact occur.

(b) Six months' survival. If the only condition which will cause the interest taken by the surviving spouse to terminate is the death of the surviving spouse and the condition is of such nature that it can occur only within 6 months following the decedent's death, the exception provided by section 2056(b)(3) will apply, provided the condition does not in fact occur. However, if the condition (unless it relates to death as a result of a common disaster) is one which may occur either within the 6-month period or thereafter, the exception provided by section 2056(b)(3) will not apply.

(c) Common disaster. If a property interest passed from the decedent to his surviving spouse subject to the condition that she does not die as a result of a common disaster which also resulted in the decedent's death, the exception provided by section 2056(b)(3) will not be applied in the final audit of the return if there is still a possibility that the surviving spouse may be deprived of the property interest by operation of the common disaster provision as given effect by the local law.

(d) Examples. The application of this section may be illustrated by the following examples:

Example (1).A decedent bequeathed his entire estate to his spouse on condition that she survive him by 6 months. In the event his spouse failed to survive him by 6 months, his estate was to go to his niece and her heirs. The decedent was survived by his spouse. It will be observed that, as of the time of the decedent's death, it was possible that the niece would, by reason of the interest which passed to her from the decedent possess or enjoy the estate after the termination of the interest which passed to the spouse. Hence, under the general rule set forth in § 20.2056(b)-1, the interest which passed to the spouse would be regarded as a nondeductible interest. If the surviving spouse in fact died within 6 months after the decedent's death, that general rule is to be applied, and the interest which passed to the spouse is a nondeductible interest. However, if the spouse in fact survived the decedent by 6 months, thus extinguishing the interest of the niece, the case comes within the exception provided by section 2056(b)(3), and the interest which passed to the spouse is a deductible interest. (It is assumed for the purpose of this example that no other factor which would cause the interest to be nondeductible is present.) Example (2).The facts are the same as in example (1) except that the will provided that the estate was to go to the niece either in case the decedent and his spouse should both die as a result of a common disaster, or in case the spouse should fail to survive the decedent by 3 months. It is assumed that the decedent was survived by his spouse. In this example, the interest which passed from the decedent to his surviving spouse is to be regarded as a nondeductible interest if the surviving spouse in fact died either within 3 months after the decedent's death or as a result of a common disaster which also resulted in the decedent's death. However, if the spouse in fact survived the decedent by 3 months, and did not thereafter die as a result of a common disaster which also resulted in the decedent's death, the exception provided under section 2056(b)(3) will apply and the interest will be deductible. Example (3).The facts are the same as in example (1) except that the will provided that the estate was to go to the niece if the decedent and his spouse should both die as a result of a common disaster and if the spouse failed to survive the decedent by 3 months. If the spouse in fact survived the decedent by 3 months, the interest of the niece is extinguished, and the interest passing to the spouse is a deductible interest. Example (4).A decedent devised and bequeathed his residuary estate to his wife if she was living on the date of distribution of his estate. The devise and bequest is a nondeductible interest even though distribution took place within 6 months after the decedent's death and the surviving spouse in fact survived the date of distribution.