(a) In general. (1) Where an individual has filed a separate return for a taxable year for which a joint return could have been made by him and his spouse under section 6013(a), and the time prescribed by law for filing the return for such taxable year has expired, such individual and his spouse may, under conditions hereinafter set forth, make a joint return for such taxable year. The joint return filed pursuant to section 6013(b) shall constitute the return of the husband and wife for such year, and all payments, credits, refunds, or other repayments, made or allowed with respect to the separate return of either spouse are to be taken into account in determining the extent to which the tax based on the joint return has been paid.

(2) If a joint return is made under section 6013(b), any election, other than the election to file a separate return, made by either spouse in his separate return for the taxable year with respect to the treatment of any income, deduction, or credit of such spouse shall not be changed in the making of the joint return where such election would have been irrevocable if the joint return had not been made. Thus, if one spouse has made an irrevocable election to adopt and use the last-in, first-out inventory method under section 472, this election may not be changed upon making the joint return under section 6013(b).

(3) A joint return made under section 6013(b) after the death of either spouse shall, with respect to the decedent, be made only by his executor or administrator. Thus, where no executor or administrator has been appointed, a joint return cannot be made under section 6013(b).

(4) A nonresidential alien treated as a resident under section 6013 (g) or (h) for any taxable year ending on or after December 31, 1975, and the alien's U.S. citizen or resident spouse may file a joint return for that taxable year, even though one or both of the spouses have previously filed separate returns for that taxable year. In this case, the rule in paragraph (a)(3) of this section does not apply.

(b) Limitations with respect to making of election. A joint return shall not be made under section 6013(b)(1) with respect to a taxable year:

(1) Beginning on or before July 30, 1996, unless there is paid in full at or before the time of the filing of the joint return the amount shown as tax upon such joint return; or

(2) After the expiration of three years from the last day prescribed by law for filing the return for such taxable year determined without regard to any extension of time granted to either spouse; or

(3) After there has been mailed to either spouse, with respect to such taxable year, a notice of deficiency under section 6212, if the spouse, as to such notice, files a petition with the Tax Court of the United States within the time prescribed in section 6213; or

(4) After either spouse has commenced a suit in any court for the recovery of any part of the tax for such taxable year; or

(5) After either spouse has entered into a closing agreement under section 7121 with respect to such taxable year, or after any civil or criminal case arising against either spouse with respect to such taxable year has been compromised under section 7122.

(c) When return deemed filed; assessment and collection; credit or refund. (1) For the purpose of section 6501, relating to the period of limitations upon assessment and collection, and section 6651, relating to delinquent returns, a joint return made under section 6013(b) shall be deemed to have been filed, giving due regard to any extension of time granted to either spouse, on the following date:

(i) Where both spouses filed separate returns, prior to making the joint return under section 6013(b), on the date the last separate return of either spouse was filed for the taxable year, but not earlier than the last date prescribed by law for the filing of the return of either spouse;

(ii) Where only one spouse was required and did file a return prior to the making of the joint return under section 6013(b), on the date of the filing of the separate return, but not earlier than the last day prescribed by law for the filing of such return; or

(iii) Where both spouses were required to file a return, but only one spouse did so file, on the date of the filing of the joint return under section 6013(b).

(2) For the purpose of section 6511, relating to refunds and credits, a joint return made under section 6013(b) shall be deemed to have been filed on the last date prescribed by law for filing the return for such taxable year, determined without regard to any extension of time granted to either spouse for filing the return or paying the tax.

(d) Additional time for assessment. In the case of a joint return made under section 6013(b), the period of limitations provided in sections 6501 and 6502 shall not be less than one year after the date of the actual filing of such joint return. The expiration of the one year is to be determined without regard to the rules provided in paragraph (c)(1) of this section, relating to the application of sections 6501 and 6651 with respect to a joint return made under section 6013(b).

(e) Additions to the tax and penalties. (1) Where the amount shown as the tax by the husband and wife on a joint return made under section 6013(b) exceeds the aggregate of the amounts shown as tax on the separate return of each spouse, and such excess is attributable to negligence, intentional disregard of rules and regulations, or fraud at the time of the making of such separate return, there shall be assessed, collected, and paid in the same manner as if it were a deficiency an additional amount as provided by the following:

(i) If any part of such excess is attributable to negligence, or intentional disregard of rules and regulations, at the time of the making of such separate return, but without any intent to defraud, this additional amount shall be 5 percent of the total amount of the excess.

(ii) If any part of such excess is attributable to fraud with intent to evade tax at the time of the making of such separate return, this additional amount shall be 50 percent of the total amount of the excess. The latter addition is in lieu of the 50 percent addition to the tax provided in section 6653(b).

(2) For purposes of section 7206 (1) and (2) and section 7207 (relating to criminal penalties in the case of fraudulent returns), the term “return” includes a separate return filed by a spouse with respect to a taxable year for which a joint return is made under section 6013(b) after the filing of a separate return.