Separate return following joint return.

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.

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.

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.

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.

A separate return may not be filed unless the amount shown upon that separate return is paid in full on or before the date when the separate return is filed.