Code of Federal Regulations Title 26. Internal Revenue § 1.153–1 Determination of marital status

For the purpose of determining the right of an individual to claim an exemption for his spouse under section 151(b), the determination of whether such individual is married shall be made as of the close of his taxable year, unless his spouse dies during such year, in which case the determination shall be made as of the time of such death. An individual legally separated from his spouse under a decree of divorce or separate maintenance shall not be considered as married. The provisions of this section may be illustrated by the following examples:

Example 1.A, who files his returns on the basis of a calendar year, married B on December 31, 1956. B, who had never previously married, had no gross income for the calendar year 1956 nor was she the dependent of another taxpayer for such year. A may claim an exemption for B for 1956.

Example 2.C and his wife, D, were married in 1940. They remained married until July 1956 at which time D was granted a decree of divorce. C, who files his income tax returns on a calendar year basis, cannot claim an exemption for D on his 1956 return as C and D were not married on the last day of C's taxable year. Had D died instead of being divorced, C could have claimed an exemption for D for 1956 as their marital status would have been determined as of the date of D's death.