If someone you love passed away and left behind property or assets in Massachusetts, you might need to file a state estate tax return even if no federal estate tax is due. Massachusetts has its own estate tax rules, separate from the IRS, and they apply at a much lower threshold than many people expect. Understanding Massachusetts estate tax filing requirements early can help avoid penalties, delays in probate, or unexpected bills during an already difficult time.

What counts as a taxable estate in Massachusetts?

Massachusetts imposes an estate tax on estates valued at more than $1 million. This includes real estate, bank accounts, investments, business interests, and even life insurance proceeds if the deceased owned the policy. Unlike the federal system, which uses portability between spouses, Massachusetts doesn’t allow unused exemptions to transfer automatically. So even if your spouse’s estate was under $1 million, your own estate could still be taxed if it exceeds that amount.

For example, if a homeowner in Boston dies with a house worth $800,000 and $300,000 in retirement accounts, the total estate is $1.1 million $100,000 over the exemption. That means a Massachusetts estate tax return (Form M-706) must be filed, and tax may be owed on the full value above $1 million, not just the excess.

When do you have to file?

The deadline to file a Massachusetts estate tax return is nine months after the date of death. If you need more time, you can request an extension but any tax due must still be paid by the original deadline to avoid interest and penalties. Late filings can delay the release of assets and complicate the estate administration process in Massachusetts, especially if real estate needs to be sold or transferred.

Common mistakes people make

  • Assuming no tax is due because there’s no federal filing requirement. The federal exemption is over $13 million (as of 2024), but Massachusetts’ $1 million threshold catches many modest estates.
  • Not including all assets. People often forget about out-of-state property, payable-on-death accounts, or jointly held assets that still count toward the estate for tax purposes.
  • Missing deductions. Debts, funeral expenses, and administrative costs can reduce the taxable estate but only if properly documented and claimed on the return.

How exemptions and deductions work

Massachusetts offers a $1 million exclusion per person. There’s no unlimited marital deduction for non-citizen spouses, and gifts made within three years of death may be pulled back into the estate. However, certain charitable bequests and debts can lower the taxable value. For more details on what might reduce your liability, see our overview of Massachusetts inheritance tax exemptions.

Note: Massachusetts does not have an inheritance tax meaning beneficiaries don’t pay tax on what they receive. The estate itself pays the tax before assets are distributed. This is a key distinction many confuse when researching “inheritance tax” versus “estate tax.”

What forms do you need?

The main form is the Massachusetts Estate Tax Return (Form M-706). You’ll also need supporting documents like the federal Form 706 (even if not filed with the IRS), appraisals, account statements, and proof of debts or expenses. A complete list of required paperwork is outlined in our guide to Massachusetts estate administration forms.

If the estate includes real estate, you’ll likely need a Certificate of Discharge of Estate Lien from the Department of Revenue before the property can be sold or retitled. Without it, the Registry of Deeds won’t record the transfer.

Do you need professional help?

Estates near or above the $1 million mark almost always benefit from legal or tax advice. Mistakes in valuation, missed deductions, or incorrect apportionment among beneficiaries can lead to overpayment or audits. Even seemingly simple cases like a single-family home with a small investment account can trigger filing obligations if the total crosses the threshold.

For context, the Massachusetts Department of Revenue provides basic instructions, but they don’t offer personalized guidance. If you’re acting as executor, it’s worth consulting someone familiar with local probate courts and state tax practices.

Next steps if you’re handling an estate

  1. Determine the date-of-death value of all assets owned by the decedent.
  2. Add up the total if it’s over $1 million, plan to file Form M-706.
  3. Gather account statements, deeds, loan documents, and funeral receipts.
  4. Review whether any inheritance tax guidelines for Massachusetts estates affect your situation, especially if beneficiaries live out of state or if the will includes charitable gifts.
  5. File the return and pay any tax due within nine months or request an extension while paying estimated tax to avoid penalties.

For official details, the Massachusetts Department of Revenue publishes current forms and filing instructions online.

Quick checklist: Is the estate over $1 million? Are all assets accounted for? Are debts and expenses documented? Is the M-706 form complete with required attachments? Has the tax been paid or properly deferred? Getting these right upfront saves time, money, and stress later.