71.09(10) (10) Overpayment. When the amount of an installment payment of estimated tax exceeds the amount determined to be the correct amount of such installment payment, the overpayment shall be credited against the unpaid installment, if any.

71.09(11)(a) (a) The tax shown on the return or, if no return is filed, the tax, minus amounts withheld under subch. X, is less than $500.

71.09(11)(b) (b) The preceding taxable year was 12 months, the taxpayer had no liability under s. 71.02 or 71.08 for that year and the taxpayer was a resident of this state for all of that year.

71.09(11)(c) (c) The secretary of revenue determines that because of casualty, disaster or other unusual circumstances it is not equitable to impose interest.

71.09(11)(d) (d) The secretary of revenue determines that the taxpayer retired during the taxable year or during the preceding taxable year after having attained age 62 or becoming disabled except that this paragraph does not apply upon a showing by the department under s. 73.16 (4).

71.09(11)(e) (e) For taxable years beginning after December 31, 2008, the taxpayer qualifies for a federal extension of time to file under 26 USC 7508A due to a presidentially declared disaster or terroristic or military action.

71.09(11)(f) (f) The taxpayer has underpaid the taxpayer's estimated taxes due to the change in brackets under s. 71.06 (1p) (e) and (2) (g) 5. and (h) 5. This paragraph applies only in the first taxable year to which these bracket changes apply.

71.09(11)(g) (g) The taxpayer has underpaid the taxpayer's estimated taxes due to the change in the percentage under s. 71.07 (5n) (b) 3. This paragraph applies only to taxable years beginning after December 31, 2014, and before January 1, 2016.

71.09(12)(a) (a) The 4th month of the taxable year.

71.09(12)(b) (b) The 6th month of the taxable year.

71.09(12)(c) (c) The 9th month of the taxable year.

71.09(12)(d) (d) The first month of the next taxable year.

71.09(13)(a)(a) Except as provided in pars. (b), (c) and (d), the amount of each installment required under sub. (12) is 25 percent of the lower of the following amounts:

71.09(13)(a)2. 2. The tax shown on the return for the preceding year. If a husband and wife who filed separate returns for the preceding taxable year file a joint return, the tax shown on the return for the preceding year is the sum of the taxes shown on the separate returns of the husband and wife. If a husband and wife who filed a joint return for the preceding taxable year file separate returns, the tax shown on the return for the preceding year is the husband's or wife's proportion of that tax based on what their respective tax liabilities for that year would have been had they filed separately.

71.09(13)(b) (b) Paragraph (a) 2. does not apply if the preceding taxable year was less than 12 months or if the taxpayer did not file a return for the preceding taxable year.

71.09(13)(c) (c) Paragraph (a) 2. does not apply if the taxpayer is an estate or trust and has a taxable income of $20,000 or more.

71.09(13)(d) (d) If 22.5 percent for the first installment, 45 percent for the 2nd installment, 67.5 percent for the 3rd installment and 90 percent for the 4th installment of the tax for the taxable year computed by annualizing, under methods prescribed by the department of revenue, the taxpayer's income for the months in the taxable year ending before the installment's due date is less than the installment required under par. (a), the taxpayer may pay the amount under this paragraph rather than the amount under par. (a). Any taxpayer who pays an amount calculated under this paragraph shall increase the next installment computed under par. (a) by an amount equal to the difference between the amount paid under this paragraph and the amount that would have been paid under par. (a). The income of any estate or trust for the months in the taxable year ending before the date one month before the due date for the installment shall be annualized in calculating the installments under this paragraph.

71.09(14) (14) Exception to final installment. If a taxpayer files a return for a calendar year on or before January 31 of the succeeding calendar year (or if a taxpayer on a fiscal year basis files a return on or before the last day of the first month immediately succeeding the close of such fiscal year) and pays in full at the time of such filing the amount computed on the return as payable, then, if estimated taxes are not required to be paid on or before the 15th day of the 9th month of the taxable year but are required to be paid on or before January 15 of the succeeding taxable year (or the date corresponding thereto in the case of a fiscal year), such return shall be considered as such payment.

71.09(15)(a)(a) Any individual deriving income from wages, as defined in s. 71.63 (6), which is subject to taxation under this chapter who pays 100 percent of the estimated tax for the following calendar or taxable year on or before the last day of the current calendar or taxable year is entitled to complete exemption from payroll withholding under subch. X for such following calendar or taxable year.

71.09(15)(b) (b) No employer shall recognize exemption from payroll withholding for any employee who does not furnish a certificate prepared by the department of revenue satisfactorily showing that the employee has paid the estimated tax within the time and manner prescribed in this subsection with respect to the calendar or taxable year for which such exemption is sought.

71.09(15)(c) (c) So far as applicable the additions to tax prescribed in this section shall apply to estimated taxes paid under this subsection.

71.09(15)(d) (d) No employer shall force or attempt to coerce an employee into estimating and prepaying his or her income taxes. The penalty under s. 71.83 (2) (a) 4. applies to any employer who violates this paragraph.

71.09(16) (16) Joint payments. Married persons may jointly pay estimated taxes unless either spouse is a nonresident alien or the spouses have different taxable years. If they do pay jointly, the provisions under this section applicable to individuals are applicable to the married persons jointly. If a married person files a separate return for a taxable year for which a joint payment was made, the payments may be allocated between themselves as they choose, but if they do not agree on an allocation the department of revenue shall allocate the payments to each spouse on the basis of the ratio of taxes shown on their separate returns or pursuant to default assessment under s. 71.74 (3). If either spouse pays separately, no part of the payment may be allocated to the other spouse.