Thus, if property acquired as the result of a compulsory or involuntary conversion of other property of the taxpayer has under section 1033(c) the same basis in whole or in part in the hands of the taxpayer as the property so converted, its acquisition is treated as an exchange and the holding period of the newly acquired property shall include the period during which the converted property was held by the taxpayer. Thus, also, where stock of a controlled corporation is received by a taxpayer pursuant to a distribution to which section 355 (or so much of section 356 as relates to section 355) applies, the distribution is treated as an exchange and the period for which the taxpayer has held the stock of the controlled corporation shall include the period for which he held the stock of the distributing corporation with respect to which such distribution was made.
The provisions of this paragraph apply to sales of such property included in the decedent's gross estate for the purposes of the estate tax by the executor or administrator of the estate and to sales of such property by other persons who have acquired property from the decedent. The provisions of this paragraph may also be applicable to cases involving joint tenancies, community property, and properties transferred in contemplation of death. Thus, if a surviving joint tenant, who acquired property by right of survivorship, sells or otherwise disposes of such property within 6 months after the date of the decedent's death, and the basis of the property in his hands is determined in whole or in part under section 1014, the property shall be considered to have been held by the surviving joint tenant for more than 6 months. Similarly, a surviving spouse's share of community property shall be considered to have been held by her for more than 6 months if it is sold or otherwise disposed of within 6 months after the date of the decedent's death, regardless of when the property was actually acquired by the marital community. For the purposes of this paragraph, it is immaterial that the sale or other disposition produces gain or loss. If property is considered to have been held for more than 6 months by reason of this paragraph, it also is considered to have been held for that period for purposes of section 1231 (if that section is otherwise applicable).
26 C.F.R. §1.1223-1