How to File a Tax Extension in Massachusetts (Form M-4868)

To file a tax extension in Massachusetts, submit Form M-4868 (or its electronic equivalent through MassTaxConnect) by April 15, 2026, and pay at least 80% of the tax you’ll owe for the year by that same date. Meet both conditions and you get an automatic six-month extension to October 15, 2026.¹ Miss the 80% threshold and the extension is void, with penalties running back to the original April 15 deadline.

Massachusetts does not ask why you need more time. The extension is automatic as long as the payment requirement is satisfied.

Filing Online Through MassTaxConnect

The fastest route is electronic, either through MassTaxConnect (the Department of Revenue’s online portal) or commercial tax software.² If your extension payment is $5,000 or more, electronic payment is mandatory. Sending a paper check at that threshold can trigger a $100 penalty on its own.³

Filing by Mail With Form M-4868

The paper form is Form M-4868, “Massachusetts Income Tax Extension Payment Worksheet and Voucher,” available on the Department of Revenue’s website. It asks for your Social Security number, which return you plan to file (Form 1 for residents or Form 1-NR/PY for nonresidents and part-year residents), and your payment amount. A worksheet walks you through estimating total tax, subtracting withholding and credits, and arriving at the balance due.⁴

Mail the form with a check or money order payable to the Commonwealth of Massachusetts to:

Mass. DOR, PO Box 419540, Boston, MA 02241-9540⁵

Either way, the extension has to be submitted on or before April 15, 2026. The Department of Revenue will not accept extensions filed after midnight on that date.¹ Keep a copy of the filing and your payment confirmation.

The 80% Payment Rule

This is where most extension problems begin. Your extension is valid only if at least 80% of your total tax liability is paid by April 15, 2026. The 80% figure counts everything already in the state’s hands or claimable on your return: Massachusetts withholding from your W-2s, estimated payments you made during the year, any prior-year overpayment you applied to this year, and credits you’ll claim.⁴ If those sources already cover 80% of your final bill, you may not need to send any additional payment with the extension.

If they don’t, send the difference. And if your payments end up below 80% of the final tax shown on the completed return, the extension is treated as void. You then face both a late-filing penalty and a late-payment penalty, calculated back to April 15.⁶ The practical takeaway: estimate on the high side. Pay a little more than you think you owe and claim the refund when you actually file.

A Federal Extension Does Not Cover Massachusetts

Filing Form 4868 with the IRS extends your federal return only. Massachusetts requires its own separate extension filing with the Department of Revenue.¹

If You Owe Nothing

If your completed return will show no tax due, Massachusetts grants the extension to October 15, 2026, automatically. No paperwork needed. But you cannot file a “zero dollar” extension if you do owe tax; in that case, a payment is required for the extension to exist at all.¹⁷

What a Void or Missing Extension Costs

Two separate penalties can apply, each at 1% of the unpaid tax per month (or fraction of a month), each capped at 25%:

Late-filing penalty: 1% per month of the unpaid tax, up to 25%, running from the original due date until you file.⁸
Late-payment penalty: 1% per month of the unpaid tax, up to 25%, running until the balance is paid in full.⁸

They stack. File late and pay late and you can face up to 50% in combined penalties on top of the tax itself.

Interest accrues on any unpaid tax from the original April 15 due date even when a valid extension is on file. The rate is the federal short-term rate plus four percentage points, compounded daily.⁹ So paying as much as you reasonably can by April 15 limits what you owe later, even if the extension itself is secure.

If April 15 passes without an extension on file and you owe tax, the Department of Revenue recommends paying immediately through a “return” payment on MassTaxConnect.¹ Every month of delay adds another 1% to each penalty. File the return itself as soon as possible to stop the late-filing clock.

Requesting Abatement for Reasonable Cause

If you get hit with penalties, Massachusetts allows the Commissioner of Revenue to waive or abate them when the failure to file or pay was due to reasonable cause rather than willful neglect.⁸ The bar is real: “I forgot” or “my accountant didn’t tell me” will not clear it. Serious illness, a natural disaster, or destruction of records are the kinds of circumstances that qualify.¹⁰ Abatement reaches only the penalties. Interest on the unpaid tax still runs.

Combat Zone Service

Military and support personnel serving in a combat zone receive an extension equal to their time served plus at least 180 days, under Massachusetts General Laws Chapter 62C, Section 81. This one covers both filing and payment, so penalties and interest do not accrue during the extended period. The rules parallel the federal provisions under Internal Revenue Code Section 7508.¹¹

1
Mass.gov. File an Extension and Pay MA Personal Income, Fiduciary, or Partnership Tax
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Mass.gov. About MassTaxConnect
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Mass.gov. DOR E-filing and Payment Requirements
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Mass.gov. Form M-4868 Massachusetts Income Tax Extension Payment Worksheet and Voucher
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Mass.gov. Mailing Addresses for Massachusetts Tax Forms
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Massachusetts Department of Revenue. AP 604 – Extensions of Time to File Tax Returns
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Massachusetts Department of Revenue. Massachusetts DOR Tax Due Dates and Extensions
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General Court of Massachusetts. Massachusetts General Law Part I Title IX Chapter 62C Section 33
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General Court of Massachusetts. Massachusetts General Law Part I Title IX Chapter 62C Section 32
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Cornell Law Institute. 830 CMR 62C.33.1 – Interest, Penalties, and Application of Payments
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Mass.gov. TIR 04-5 – Massachusetts Income Tax Filing Extensions for Military Personnel in a Combat Zone