(a) General rule. The determination of whether an individual is married shall be made as of the close of his taxable year unless his spouse dies during his taxable year, in which case such determination shall be made as of the time of such death; and, except as provided in paragraph (b) of this section, an individual shall be considered as married even though living apart from his spouse unless legally separated under a decree of divorce or separate maintenance. The provisions of this paragraph may be illustrated by the following examples:
Taxpayer A and his wife B both make their returns on a calendar year basis. In July 1954, they enter into a separation agreement and thereafter live apart, but no decree of divorce or separate maintenance is issued until March 1955. If A itemizes and claims his actual deductions on his return for the calendar year 1954, B may not elect the standard deduction on her return since B is considered as married to A (although permanently separated by agreement) on the last day of 1954.
Taxpayer A makes his returns on the basis of a fiscal year ending June 30. His wife B makes her returns on the calendar year basis. A died in October 1954. In such case, since A and B were married as of the date of death, B may not elect the standard deduction for the calendar year 1954 if the income of A for the short taxable year ending with the date of his death is determined without regard to the standard deduction.
(b) Certain married individuals living apart.
(1) For purposes of Part IV of Subchapter B of Chapter 1 of the Code, an individual is not considered as married for taxable years beginning after December 31, 1969, if
(i) such individual is married (within the meaning of paragraph (a) of this section) but files a separate return;
(ii) such individual maintains as his home a household which constitutes for more than one-half of the taxable year the principal place of abode of a dependent (a) who (within the meaning of section 152 and the regulations thereunder) is a son, stepson, daughter, or stepdaughter of the individual, and (b) with respect to whom such individual is entitled to a deduction for the taxable year under section 151; (iii) such individual furnishes over half of the cost of maintaining such household during the taxable year; and (iv) during the entire taxable year such individual's spouse is not a member of such household.
(2) For purposes of subparagraph (1)(ii)(a) of this paragraph, a legally adopted son or daughter of an individual, a child (described in paragraph (c)(2) of § 1.152-2) who is a member of an individual's household if placed with such individual by an authorized placement agency (as defined in paragraph (c)(2) of § 1.152-2) for legal adoption by such individual, or a foster child (described in paragraph (c)(4) of § 1.152-2) of an individual if such child satisfies the requirements of section 152(a)(9) of the Code and paragraph (b) of § 1.152-1 with respect to such individual, shall be treated as a son or daughter of such individual by blood.
(3) For purposes of subparagraph (1)(ii) of this paragraph, the household must actually constitute the home of the individual for his taxable year. However, a physical change in the location of such home will not prevent an individual from qualifying for the treatment provided in subparagraph (1) of this paragraph. It is not sufficient that the individual maintain the household without being its occupant. The individual and the dependent described in subparagraph (1)(ii)(a) of this paragraph must occupy the household for more than one-half of the taxable year of the individual. However, the fact that such dependent is born or dies within the taxable year will not prevent an individual from qualifying for such treatment if the household constitutes the principal place of abode of such dependent for the remaining or preceding part of such taxable year. The individual and such dependent will be considered as occupying the household during temporary absences from the household due to special circumstances. A nonpermanent failure to occupy the common abode by reason of illness, education, business, vacation, military service, or a custody agreement under which a child or stepchild is absent for less than 6 months in the taxable year of the taxpayer, shall be considered a temporary absence due to special circumstances. Such absence will not prevent an individual from qualifying for the treatment provided in subparagraph (1) of this paragraph if
(i) it is reasonable to assume that such individual or the dependent will return to the household and
(ii) such individual continues to maintain such household or a substantially equivalent household in anticipation of such return.
(4) An individual shall be considered as maintaining a household only if he pays more than one-half of the cost thereof for his taxable year. The cost of maintaining a household shall be the expenses incurred for the mutual benefit of the occupants thereof by reason of its operation as the principal place of abode of such occupants for such taxable year. The cost of maintaining a household shall not include expenses otherwise incurred. The expenses of maintaining a household include property taxes, mortgage interest, rent, utility charges, upkeep and repairs, property insurance, and food consumed on the premises. Such expenses do not include the cost of clothing, education, medical treatment, vacations, life insurance, and transportation. In addition, the cost of maintaining a household shall not include any amount which represents the value of services rendered in the household by the taxpayer or by a dependent described in subparagraph (1)(ii)(a) of this paragraph.
(5) For purposes of subparagraph (1)(iv) of this paragraph, an individual's spouse is not a member of the household during a taxable year if such household does not constitute such spouse's place of abode at any time during such year. An individual's spouse will be considered to be a member of the household during temporary absences from the household due to special circumstances. A nonpermanent failure to occupy such household as his abode by reason of illness, education, business, vacation, or military service shall be considered a mere temporary absence due to special circumstances.
(6) The provisions of this paragraph may be illustrated by the following example:
Taxpayer A, married to B at the close of the calendar year 1971, his taxable year, is living apart from B, but A is not legally separated from B under a decree of divorce or separate maintenance. A maintains a household as his home which is for 7 months of 1971 the principal place of abode of C, his son, with respect to whom A is entitled to a deduction under section 151. A pays for more than one-half the cost of maintaining that household. At no time during 1971 was B a member of the household occupied by A and C. A files a separate return for 1971. Under these circumstances, A is considered as not married under section 143(b) for purposes of the standard deduction. Even though A is married and files a separate return A may claim for 1971 as his standard deduction the larger of the low income allowance up to a maximum of $1,050 consisting of both the basic allowance and additional allowance (rather than the basic allowance only subject to the $500 limitation applicable to a separate return of a married individual) or the percentage standard deduction subject to the $1,500 limitation (rather than the $750 limitation applicable to a separate return of a married individual). See § 1.141-1. For purposes of the provisions of part IV of subchapter B of chapter 1 of the Code and the regulations thereunder, A is treated as unmarried.