How to Fill Out Missouri Form MO W-4: Employee Withholding Certificate

To fill out Missouri Form MO W-4, enter your name, Social Security number, and address at the top, check one filing status box on Line 1, use Lines 2 through 4 only if you need extra withholding, reduced withholding, or a full exemption, then sign, date, and give the form to your employer’s payroll or HR department. You never mail it to the Missouri Department of Revenue. The current version is a short PDF posted on the Department of Revenue’s website.¹

Start With Your Personal Information

At the top of the form, write your full legal name exactly as it appears on your Social Security card, your nine-digit Social Security number, and your current mailing address. Below that are four numbered lines. Most employees only need Line 1.

Line 1: Pick Your Filing Status

Line 1 asks you to check one of three boxes.¹

Single or Married Spouse Works or Married Filing Separate. Pick this if you’re unmarried, if you’re married but your spouse also earns income, or if you plan to file a separate Missouri return from your spouse.
Married (Spouse does not work). Pick this only if your spouse has no income. It applies a larger standard deduction in the withholding formula ($32,200 for 2026, compared with $16,100 for the statuses above), so less tax is withheld from each paycheck.²
Head of Household. Pick this if you’re unmarried and pay more than half the cost of keeping up a home for a qualifying dependent. The 2026 standard deduction built into this status is $24,150.²

You don’t enter the standard deduction yourself. Your employer’s payroll system reads the status you checked and applies the right amount automatically.

Line 2: Ask for Extra Withholding

Line 2 is where you tell your employer to pull additional state tax from each paycheck. Use it if you have income that isn’t subject to withholding on its own, such as investment dividends, freelance work, rental income, or a second job you’d rather cover through your main paycheck. Estimate how much additional Missouri tax you expect to owe for the year, divide by the number of pay periods, and enter that per-period dollar amount on Line 2.¹

Line 3: Ask for Reduced Withholding

Line 3 does the opposite. If you consistently get a large Missouri refund because itemized deductions, credits, or other modifications drop your actual tax well below the standard formula, you can enter a specific flat dollar amount on Line 3. Your employer will then withhold exactly that amount per pay period instead of running the normal calculation. Leave Line 3 blank and the standard formula applies.¹

Be careful with this one. If Line 3 is too low, you’ll be under-withheld and could owe a balance plus a penalty at tax time. To stay inside Missouri’s safe harbor, your total withholding and estimated payments should cover at least 100 percent of the tax shown on your prior-year return (assuming a full 12-month year) or at least 90 percent of your current-year liability.³

Line 4: Claim an Exemption

If you qualify for a complete exemption from Missouri withholding, write “EXEMPT” on Line 4 and check the box that matches your reason. The form lists three qualifying situations.¹

No tax liability. You received a full refund of all Missouri income tax withheld last year and expect to owe nothing this year.
Military spouse. You qualify under the Servicemembers Civil Relief Act (as amended by the Military Spouses Residency Relief Act) and have no Missouri tax liability.
Active-duty military. Your income is earned as a member of an active-duty branch of the U.S. Armed Forces and you’re eligible for Missouri’s military income deduction.

An exempt MO W-4 expires at the end of the calendar year. If you still qualify, file a new one each January to keep the exemption in place.¹

Sign, Date, and Hand It to Payroll

The form isn’t valid without your signature. By signing, you certify under penalty of perjury that the information is true and accurate. Enter the date you actually sign; backdating isn’t allowed.⁴

Give the completed form to your employer’s payroll or HR department. The form itself says “Return completed form to your Employer.” Your employer keeps the original and uses the data to set your withholding in their payroll system.¹

Keep a copy for yourself. When your first paycheck under the new withholding arrives, compare the state tax line on your pay stub against what you expected. If the numbers don’t match your instructions, contact payroll quickly. Catching an error in February is much easier to fix than finding it in April.

If you never turn in a MO W-4, your employer doesn’t skip Missouri withholding. They default to the highest rate, calculating as if you’re single with no adjustments, which usually produces the largest deduction from each paycheck.⁴ You’ll get the excess back when you file your return, but the money sits with the state in the meantime.

When to File a New Form

Any life event that changes your filing status or tax picture is a reason to submit an updated MO W-4. Common triggers include getting married or divorced, a spouse starting or stopping work, gaining or losing a dependent, and taking on a second job. Missouri law requires employers to withhold an amount “substantially equivalent to the tax reasonably estimated to be due” based on your wages, so keeping the form current protects both of you.⁵

If you claimed exempt status on Line 4, remember the annual renewal. File a brand-new MO W-4 every year or your employer reverts to the standard withholding formula.¹

When the MO W-4 Isn’t the Right Form

The MO W-4 covers employees working in Missouri. Two related forms handle situations the standard form doesn’t fit:

Form MO W-4C, for Missouri residents who work in another state. If 100 percent of your work is performed in another state and that state already withholds income tax, you can use the MO W-4C to request that your employer skip Missouri withholding. If you split your work between Missouri and another state, you use it to request Missouri withholding only on the Missouri portion.⁶
Form MO W-4P, for retirees receiving pension or annuity payments. Missouri withholding from pensions is voluntary, not automatic. You can elect to have nothing withheld or specify a monthly amount of at least $10.⁷

1
Missouri Department of Revenue. Form MO W-4 – Employee’s Withholding Certificate
2
Missouri Department of Revenue. 2026 Missouri Withholding Tax Formula
3
Missouri Department of Revenue. Declaration of Estimated Tax for Individuals
4
Missouri State University. Guidelines for Completing Federal and Missouri W-4
5
Missouri Revisor of Statutes. Missouri Code 143.191 – Employer to Withhold Tax From Wages
6
Missouri Department of Revenue. Form MO W-4C – Withholding Affidavit for Missouri Residents
7
Missouri Department of Revenue. Form MO W-4P – Withholding Certificate for Pension or Annuity Statements