71.03(2)(j)2.2. Only one spouse filed a separate return before filing the joint return and the other spouse had less than $3,420 of gross income for that taxable year, on the day of the filing of that separate return, but not earlier than the last day prescribed by law for the filing of that separate return.

71.03(2)(k)(k) Filing date assumed. For purposes of s. 71.75, a joint return filed under this section is deemed to be filed on the last day prescribed by law for filing the return for that taxable year, determined without regard to any extension of time granted to either spouse.

71.03(2)(L)(L) Limits extended. If a joint return is filed under this section, the periods of limitations under ss. 71.74 to 71.77 and subch. XV on the making of assessments and the beginning of levy or of a proceeding in court for collection shall, with respect to the return, be extended to the extent necessary to include one year immediately after the date of the filing of the joint return, computed without regard to par. (j).

71.03(2)(m)1.1. Except as provided in subds. 3. and 5., for a taxable year for which a joint return has been filed, separate returns may be filed by the spouses on or before the last day prescribed by law for timely filing the return of either has elapsed.

71.03(2)(m)2.2. If a husband and wife change from a joint return to separate returns within the time prescribed in subd. 1., the tax paid on the joint return shall be allocated between them in proportion to the tax liability shown on each separate return.

71.03(2)(m)3.3. In the taxable year in which the death of one or both spouses occurs, a separate return may be filed under this paragraph within the time prescribed in subd. 1., or as provided for a personal representative under par. (e) if a joint return has been filed under par. (e) by the surviving spouse or by the decedent’s personal representative and the surviving spouse. If a separate return is filed by the surviving spouse or by the decedent’s personal representative under this paragraph, the joint return previously filed shall be the separate return of the surviving spouse or the decedent for whom the separate return was not filed, unless both the surviving spouse and the decedent’s personal representative file a separate return under this paragraph. The tax on the separate return of the surviving spouse shall be determined by excluding all items properly includable in the separate return of the decedent, and the tax on the separate return of the decedent shall be determined by excluding all items properly includable in the return of the surviving spouse.

71.03(2)(m)4.4. The time allowed the personal representative to disaffirm the joint return by the filing of a separate return does not establish a new due date for the return of the deceased spouse, and sub. (8) and ss. 71.91 and 71.92 apply to that return.

71.03(3)(3) Fractional part of year. If a natural person or fiduciary files a federal income tax return for a fractional part of the year, the person shall file a Wisconsin income tax return for that fractional year. That person shall compute and report income on the basis of the period for which that return is filed, and that fractional year shall constitute a taxable year.

71.03(4)(4) Election to have department compute tax.

71.03(4)(a)(a) Natural persons whose total income is not in excess of $10,000 and consists entirely of wages subject to withholding for Wisconsin tax purposes and not more than $200 total of dividends, interest and other wages not subject to Wisconsin withholding, and who have elected the Wisconsin standard deduction and have not claimed either the credit for homestead property tax relief or deductions for expenses incurred in earning such income, shall, at their election, not be required to record on their income tax returns the amount of the tax imposed on their Wisconsin taxable income. Married persons shall be permitted this election only if the joint income of the husband and wife does not exceed $10,000, if both report their incomes on the same joint income tax return form, and if both make this election.

71.03(4)(b)(b) The department shall compute the tax on income reported by persons making the election under par. (a). After applying all known applicable credits, the department shall notify the taxpayer of the amount of taxes due or the amount of taxes to be refunded.

71.03(5)(5) Copy of federal return. To the extent necessary for the administration of the tax imposed by this chapter, when required under rules prescribed or orders issued by the department or upon the written request of the department, natural persons and fiduciaries subject to this chapter shall file with the department a true and complete copy of their federal income tax return and any other return or statement filed with, or made to, or any document received from, the internal revenue service.

71.03(6)(6) Time return required.

71.03(6)(a)(a) Reports required under this section shall be made to the department of revenue on or before the date required to file the corresponding federal income tax return, not including any extension, to the internal revenue service, in the manner and form prescribed by the department of revenue, whether notified to do so or not. Such persons shall be subject to the same penalties for failure to report as those who receive notice. If the taxpayer is unable to make his or her own return, the return shall be made by a duly authorized agent or by the guardian or other person charged with the care of the person or property of such taxpayer.

71.03(6m)(6m) Time to file claims; no return required. A claim for a credit under [s. 71.07 (3m) or] subch. VIII or IX that is filed by a natural person who is not required to file a report under sub. (2) (a) shall be filed on a calendar year basis in conformity with the filing requirements in subs. (6) and (7).

71.03(7)(7) Extension of time to file. Returns of natural persons and fiduciaries that require a statement of amounts or information contained or entered on a corresponding return under the internal revenue code shall be filed within the time fixed under that code for filing of the corresponding federal return. Any extension of time granted by law or by the internal revenue service for the filing of that corresponding federal return extends the time for filing under this chapter if a copy of the taxpayer’s application to the internal revenue service requesting the extension is filed with the return under this chapter or if a copy of any request for an extension required by the internal revenue service is filed with the return under this chapter or at an earlier date that the department prescribes by rule and if the taxpayer pays the Wisconsin tax in the manner applicable to federal income taxes under the internal revenue code. Taxes payable upon the filing of the return do not become delinquent during the period of an extension but are subject to interest at the rate of 12 percent per year during such period except as follows:

71.03(7)(a)(a) For taxable years beginning after December 31, 1989, and before January 1, 1991, for persons who served in support of Operation Desert Shield, Operation Desert Storm or an operation that is a successor to Operation Desert Shield or Operation Desert Storm in the United States, or for persons who served in Egypt, Israel, Diego Garcia or Germany, or for persons who qualify for a federal extension of time to file under 26 USC 7508, who served outside the United States because of their participation in Operation Desert Shield, Operation Desert Storm or an operation that is a successor to Operation Desert Shield or Operation Desert Storm in the Desert Shield or Desert Storm theater of operations.

71.03(7)(b)(b) For taxable years beginning after December 31, 1994, and before January 1, 1997, for persons who served in support of Operation Balkan Endeavor or an operation that is a successor to Operation Balkan Endeavor, or for persons who served in Croatia, Bosnia and Herzegovina, Serbia, Macedonia, Montenegro, Hungary, Austria, Slovakia, Czech Republic or Slovenia, or for persons who qualify for a federal extension of time to file under 26 USC 7508, who served outside the United States because of their participation in Operation Balkan Endeavor or an operation that is a successor to Operation Balkan Endeavor in the Balkan Endeavor theater of operations.

71.03(7)(c)(c) For taxable years beginning after December 31, 2000, and before January 1, 2003, for persons who served in support of Operation Enduring Freedom or an operation that is a successor to Operation Enduring Freedom in the United States, or for persons who qualify for a federal extension of time to file under 26 USC 7508, who served outside the United States because of their participation in Operation Enduring Freedom or an operation that is a successor to Operation Enduring Freedom in the Enduring Freedom theater of operations.