How to Fill Out the MO W-4: Missouri Employee’s Withholding Certificate

To fill out the MO W-4, download the current one-page “Employee’s Withholding Certificate” from the Missouri Department of Revenue, enter your name, Social Security number, and address at the top, check one filing-status box on line 1, add a dollar amount on line 2 or line 3 only if you want more or less than the standard withholding, write “EXEMPT” on line 4 only if you qualify, then sign, date, and return the form to your employer’s payroll office.¹

Before You Start

Get the current form from the Missouri Department of Revenue’s forms page at dor.mo.gov, or use the printed copy your employer hands you during onboarding.² Check the title. The current version, revised in December 2024, reads “Employee’s Withholding Certificate” and has four numbered lines. If yours says “Employee’s Withholding Allowance Certificate” and asks for numbered allowances, it is outdated and should be replaced.

The top of the form asks for your full legal name, Social Security number, and home address. Use the same name and SSN that appear on your federal return so the withholding ties to the right Missouri tax account.¹

Line 1: Filing Status

Check exactly one box. Your choice is the single biggest factor in how much Missouri tax comes out of each paycheck, because each status carries a different standard deduction that gets subtracted before withholding is calculated.¹

Single, or Married Spouse Works, or Married Filing Separate. Check this if you are unmarried, if you are married but your spouse also earns income, or if you and your spouse plan to file separate Missouri returns. Standard deduction for withholding: $16,100.
Married (Spouse does not work). Check this only if you are married and your spouse has no income. The standard deduction doubles to $32,200, so less is withheld from each check.
Head of Household. Check this if you are unmarried and pay more than half the cost of keeping up a home for a qualifying dependent. Standard deduction: $24,150.

Pick carefully. Checking “Married (Spouse does not work)” when your spouse actually earns income will leave you under-withheld and facing a balance due when you file your Missouri return.

Line 2: Additional Withholding

Use line 2 if you expect the standard calculation to leave you short. Enter a flat dollar amount, and your employer will add that amount to every paycheck’s Missouri withholding.¹

The form suggests dividing your expected extra balance due by the number of pay periods in the year. If you expect to owe an extra $600 from freelance income and get paid every two weeks, enter $23 ($600 ÷ 26). This line is most useful when you have investment income, a side job, or rental income that no employer is withholding on. Leave it blank if you don’t need extra withheld.

Not sure of the amount? Run your numbers through the free Missouri withholding calculator at mytax.mo.gov, which estimates your annual state tax based on your income, filing status, and deductions.³

Line 3: Reduced Withholding

Line 3 works the other way. If you regularly get a large Missouri refund because of itemized deductions, credits, or other adjustments, you can enter a specific dollar amount here that replaces the standard withholding calculation entirely.¹

Divide your expected total Missouri tax for the year by your number of pay periods and enter that figure. Be conservative. Set it too low and you’ll end up under-withheld, with a balance due plus interest when you file. Leave line 3 blank if you want the standard formula based on your filing status.

Do not use lines 2 and 3 together. One adds to standard withholding; the other replaces it.

Line 4: Exempt Status

Write “EXEMPT” on line 4 only if you fall into one of three categories: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. You must show your employer supporting documentation: a military ID card, your spouse’s leave and earnings statement or W-2, and proof of your own out-of-state residency such as a driver’s license or voter registration card from your home state.
Active-duty military. Your income comes from active-duty service in the U.S. Armed Forces and you qualify for the military income deduction.

If you claim the no-tax-liability exemption, you have to file a new MO W-4 every year to keep it in effect. If you let it lapse, your employer goes back to standard withholding.

Sign, Date, and Return the Form

Sign and date the bottom of the form and hand it to your employer’s payroll or human resources department. The form itself says “Return completed form to your Employer,” not to the state.¹ Your employer forwards a copy to the Missouri Department of Revenue on your behalf.⁴

If you never turn in an MO W-4, payroll doesn’t skip withholding. It defaults to the single filing status at the highest rate until you submit a completed form. For most people, that means more money leaves each check than necessary, so file the form on your first day.

Keep a personal copy. Your employer is required to retain the form for state inspection, but your own record makes it easier to catch payroll errors.

When to Fill Out a New One

There is no annual requirement to resubmit the MO W-4 unless you claimed exempt status on line 4. Otherwise, file an updated form whenever something changes your Missouri tax picture:

Marriage or divorce. Your filing status and standard deduction change.
Spouse starts or stops working. If your spouse takes a job, switch from “Married (Spouse does not work)” to the “Single or Married Spouse Works” box, or you’ll be under-withheld.
Major income change. A large raise, a second job, or losing a source of income shifts what you owe. Recalculate whether you need an amount on line 2 or line 3.
New credits or deductions. If you become eligible for a Missouri tax credit that significantly reduces your liability, a reduced amount on line 3 can keep more money in each paycheck rather than in a year-end refund.

Most employers apply the change within one or two pay cycles after you submit the new form. The federal Form W-4 is a separate document with its own structure and calculations; updating one does not update the other, so if a life event affects both, file a new form with each.⁵

1
Missouri Department of Revenue. Form MO W-4 – Employee’s Withholding Certificate
2
Missouri Department of Revenue. Forms and Manuals
3
Missouri Department of Revenue. Tax Calculators
4
Legal Information Institute. Missouri Code of State Regulations 12 CSR 10-2.015 – Withholding of Tax
5
Internal Revenue Service. About Form W-4, Employee’s Withholding Certificate