Massachusetts M-4 Explained: Line-by-Line Exemptions and Withholding

The Massachusetts M-4 form is the state withholding certificate you give your employer so the right amount of Massachusetts income tax comes out of each paycheck. You claim exemptions for yourself, a spouse, and dependents; your employer plugs the total into the state withholding tables; and the number of exemptions you claim decides how much tax is deducted.¹ Massachusetts taxes wages at a flat 5%, with an additional 4% surtax on taxable income above $1,107,750 for 2026.² Getting the exemption count right keeps you from owing a surprise bill in April or lending the state money interest-free all year.

One thing to clear up before you start: the M-4 is a Massachusetts form and has nothing to do with the federal W-4 you also filled out. Claiming “Exempt” on your W-4 does not exempt you from Massachusetts withholding. To be exempt on the state side, you must have owed no Massachusetts income tax the prior year and expect to owe none this year.¹

Filling Out the M-4 Line by Line

The form has four numbered exemption lines that build a total, a fifth line for extra withholding, and four checkboxes that adjust the calculation in other ways.¹

Line 1: Personal Exemption

Enter “1” for yourself. If you are 65 or older, or will turn 65 before the start of next year, enter “2” instead. The extra count reflects the age-related exemption in Massachusetts tax law.

Line 2: Spousal Exemption

If you are married and your spouse is not claiming this exemption on their own M-4 and is not otherwise subject to Massachusetts withholding, enter “4.” That figure reflects the $4,400 spousal exemption. If your spouse also qualifies for the age 65-or-older exemption, enter “5” instead.

Line 3: Dependents

Enter the number of people who qualify as your dependents under federal income tax rules. There is one bonus: if any of your dependents will be under age 12 at year-end, add one more to your Line 3 total. That extra exemption loosely accounts for the Massachusetts child and family tax credit, which is worth $440 per eligible dependent for 2026.³

Line 4: Total Exemptions

Add Lines 1, 2, and 3. This is the number your employer feeds into the withholding tables.

Line 5: Additional Withholding

Line 5 lets you request a flat dollar amount withheld from every paycheck on top of the standard calculation. It is useful if you have investment income, rental income, or side business income that isn’t already subject to Massachusetts withholding. Bumping up your paycheck withholding here can replace quarterly estimated payments.

Checkboxes A Through D

Four checkboxes below the numbered lines change withholding without changing your exemption number:

Box A, Head of Household. Check this if you will file as head of household. It produces a small additional reduction in withholding, roughly $120 per year under the 2026 tables.
Box B, Blindness (employee). Check this if you are legally blind. It reduces your withholding by about $110 per year.
Box C, Blindness (spouse). Check this if your spouse is blind and is not subject to withholding.
Box D, Full-time student. Check this if you are a full-time student working seasonal, part-time, or temporary jobs and your annual income will not exceed $8,000. With Box D checked, your employer withholds no Massachusetts income tax at all.

The head-of-household and blindness adjustments are built into the Circular M tables as specific dollar offsets subtracted after the base tax is calculated.²

What Each Exemption Is Worth

Each exemption shields a slice of your wages from withholding. For 2026, someone claiming one exemption shelters $4,400 of annual wages. If you claim more than one, the formula is $1,000 per exemption plus $3,400.² A single filer with one exemption shelters $4,400; a married employee claiming six exemptions shelters $9,400.

There is also a low-wage floor. If you claim at least one exemption and your wages fall below $154 per week, $308 biweekly, or $8,000 per year, your employer withholds nothing at all.²

Adjusting Exemptions Up or Down

You can nudge your Line 4 total off the strict count if you want to fine-tune withholding. If you expect substantial state tax credits, raising your exemption count slightly reduces withholding and keeps more cash in your pocket during the year. The child and family tax credit alone is worth $440 per eligible child under 13, disabled dependent, or dependent age 65 and over.³

Going the other direction, if you hold a second job or expect significant non-wage income, reducing your exemption count (even to zero) increases withholding and helps you avoid an underpayment charge. The threshold for owing an underpayment addition in Massachusetts is only $400 in tax due after withholding and credits.⁴ Interest on any underpayment runs at the federal short-term rate plus four percentage points, compounded daily; for the first quarter of 2026, that is 8%.⁵

What Happens If You Don’t Turn In an M-4

If you fail to give your employer a signed M-4, state law treats your exemption count as zero.⁶ Your employer then withholds at the highest rate for your filing status with no exemption offset. You will get the excess back as a refund after you file, but the state holds your money until then.

The same zero treatment applies to the full-time student exception. Your employer cannot skip withholding unless you have actually checked Box D and signed the form.

How to Submit and When to Update It

Give the completed M-4 directly to your employer. You do not file it with the Massachusetts Department of Revenue.¹ Your employer keeps it on file and runs the calculation from it each pay period. The certificate stays in effect until you replace it.

A new M-4 takes effect at the start of the first payroll period ending on or after the date you submit it.⁶

The 10-Day Rule When Exemptions Drop

If your exemption count decreases for any reason, you are required to file a new M-4 within 10 days. Common triggers are divorce or legal separation, a dependent aging out of eligibility, or a spouse starting a job and claiming their own exemption. The statute frames this as a duty, not a suggestion.⁶ Skip it, and your employer keeps under-withholding, which usually means tax plus interest at filing time.

If your exemption count goes up, say from a new baby, you can submit an updated M-4 but you are not required to. The consequence of leaving it alone is over-withholding until you do, with the difference coming back as a refund.

A Note on the 4% Surtax

Income above $1,107,750 in 2026 is subject to an additional 4% surtax on top of the flat 5%, and Massachusetts withholds at 9% on wages above that threshold.⁷ The surtax is baked into the Circular M tables, so your employer applies it automatically. There is nothing extra to fill out on the M-4. If a large share of your income is non-wage (capital gains, business distributions), payroll withholding won’t capture it, and Line 5 or separate estimated payments become the fix.

The M-4 only controls how tax is collected during the year. Your actual liability is settled when you file Form 1, or Form 1-NR/PY if you are a part-year resident or nonresident. The point of getting the M-4 right is keeping those two numbers close so filing season holds no surprises.

1
Mass.gov. Form M-4 Massachusetts Employee’s Withholding Exemption Certificate
2
Mass.gov. Massachusetts Circular M Income Tax Withholding Tables at 5.0% Effective January 1, 2026
3
Mass.gov. Massachusetts Child and Family Tax Credit
4
General Court of Massachusetts. Massachusetts General Laws Chapter 62B Section 14
5
Mass.gov. TIR 25-8: Interest Rate On Overpayments And Underpayments
6
General Court of Massachusetts. Massachusetts General Laws Chapter 62B Section 4
7
Mass.gov. Massachusetts 4% Surtax on Taxable Income