Part III Instructions - Regular Method
A. Purpose of the Form - Use this form to determine whether your income tax was sufficiently paid throughout the year by withholding or by estimated
tax payments. If it is not, you may owe a penalty on the underpaid amount.
B. Filing an Estimated Tax Payment and Paying the Tax for Calendar Year Taxpayers -If you file returns on a calendar year basis and are required to
file Form MO-1040ES, you are generally required to file an estimated tax payment by April 15, and to pay the tax in four installments. If you are not
required to file an estimated tax payment until later in the year because of a change in your income or exemptions, you may be required to pay fewer
installments. The chart below shows the due date for the estimated tax payments and the maximum number of installments required for each.
Period Requirements First Met Due Date of Estimated Tax Payments Maximum Number of Installments Required
Between Jan. 1 and Apr. 1 April 15 4
Between Apr. 2 and Jun. 1 June 15 3
Between Jun. 2 and Sept.1 Sept. 15 2
After Sept. 1 Jan. 15 1
When the due date falls on a Saturday, Sunday, or legal holiday, the estimated tax payment will be considered timely if filed on the next business day.
C. Fiscal Year Taxpayers - Fiscal year taxpayers should substitute for the due dates above, the 15th day of the first and last months of the second
quarter of your fiscal year; the 15th day of the last month of the third quarter; and the 15th day of the first month of your next fiscal year.
D. Exception to the Penalty - You will not be liable for a penalty if your 2021 tax payments (amounts shown on Line 20) equal or exceed any amount
determined for the same period under the following exception provisions. You may apply a different exception to each underpayment. Please
enclose a separate computation page for each payment. If one of the exceptions apply, complete Lines 15 through Line 29.
The percentages shown on Lines 21, 22, and 23, for the April 15, June 15, and Sept. 15 installment dates, are for calendar year taxpayers required
to pay installments on four dates.
Exception 1 - Prior Year’s Tax - This exception applies if your 2021 tax payments equal or exceed the tax shown on your 2020 tax return. The 2020
return must cover a period of 12 months and show a tax liability.
Exception 2 - Tax on Prior Year’s Income using 2021 Rates and Exemptions - This exception applies if your 2021 tax withheld and estimated tax
payments equal or exceed the tax that would have been due on your 2020 income if you had computed it at 2021 rates. To determine if you qualify
for this exception, use the other facts and law applicable to your 2020 return.
Exception 3 - Tax on Annualized 2021 Income - This exception applies if your 2021 tax payments equal or exceed 90 percent of the tax on your
annualized taxable income for periods from the first of the year to the end of the month preceding that month in which an installment is due.
To annualize your taxable income, follow these four steps.
(a) Figure your adjusted gross income less itemized deductions from the first of your tax year up to and including the month prior to that month in
which an installment is due; or, if you use the standard deduction, figure your adjusted gross income for that period.
(b) Divide the result of step (a) by the number of months in your computation period.
(c) Multiply the result of step (b) by 12.
(d) Subtract the deduction for federal tax and, if you did not itemize, subtract the standard deduction. The result is your annualized taxable income.
Exception 3 may not be used for the fourth installment period.
Example I (Combined return)
1. Wages, received during January through March . . . . . . . . . . . . . . . . . . . . . . . . . . . . $16,000
2. Self-employment income during January through March . . . . . . . . . . . . . . . . . . . . . . . . $14,000
3. Adjusted gross income . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $30,000
4. Annualized income ($30,000 ÷ 3 x 12) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $120,000
5. Less:
(a) Standard deduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $25,100
6. Annualized taxable income . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $94,900
7. Income Tax (from Missouri tax chart) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . $4,938
8. Required installment of the estimated payment based on annualized income ($4,938 x 22.5%). . . . $1,111
If your tax withheld and estimated tax payment for the first installment period of 2021 were at least $1,111 (22.5 percent of $4,938), you do not owe
a penalty for that period.
Exception 4 - Tax on Income Over the First, Second, and Third Quarters - This exception applies if your 2021 tax payments equal or exceed 90
percent of the tax on your taxable income for periods starting from the first of the year to the end of the month preceding that in which an installment
is due. This exception does not apply to the fourth quarter. To determine if this exception applies for the first three quarters, figure your taxable
income from January 1, 2021, to the end of the month preceding that month in which an installment is due. Then compute your tax on that amount
as though it represented your taxable income for 2021.
Example II (Combined return using standard deduction)
(1) (2) (3) (4) (5)
Computation Period Income Tax 90 percent of Tax Tax Withheld
Jan. 1 to March 31 $15,000 $0 $0 $275
Jan. 1 to May 31 $30,000 $117 $105 $458
Jan. 1 to Aug. 31 $35,000 $348 $313 $733
Since the amounts in column (5) are greater than those in column (4) for each of the first three computation periods, there is no
penalty for the first two installment periods.
