When Is the Estate Tax Return Due? Extensions, Installments, Penalties

The federal estate tax return, Form 706, is due nine months after the date of death.¹ An automatic six-month extension is available if the executor files Form 4768 by that original due date, but the extension only covers filing the paperwork. The tax itself still has to be paid within the nine months.

How the Nine-Month Clock Is Counted

The clock starts on the exact date of death. Someone who dies on March 15 has a return due December 15 of the same year. When the ninth month is shorter than the month of death, the deadline falls on the last day of that month; a death on May 31, for example, produces a February deadline that lands on February 28 or 29.¹ If the calculated date is a Saturday, Sunday, or federal holiday, the deadline shifts to the next business day.

The executor or personal representative named in the will, or appointed by the probate court, is the person on the hook for filing. Nine months sounds generous and usually isn’t. Getting real estate appraised, tracking down financial accounts, valuing business interests, settling debts, and coordinating with attorneys and CPAs eats most of the window. Executors who wait until month seven to start assembling the return almost always end up asking for more time.

Do You Even Have to File?

Most estates don’t. Form 706 is required only when the gross estate, plus taxable gifts the person made during their lifetime, exceeds the basic exclusion amount for the year of death.² For deaths in 2026, that threshold is $15 million per person.³ The One, Big, Beautiful Bill Act (Public Law 119-21), signed on July 4, 2025, made this figure permanent and indexed it for inflation. Above the threshold, graduated rates apply, topping out at 40%.⁴

The threshold isn’t just about assets owned at death. Lifetime taxable gifts, meaning gifts that exceeded the annual exclusion in the year they were made, are added back when checking whether the estate crosses the line.⁵ Someone who gave away $3 million in taxable gifts and died with $13 million in assets has a $16 million combined figure, and a filing requirement.

Filing Below the Threshold for Portability

Even an estate well under $15 million may have reason to file. When the deceased was married, the executor can elect portability, letting the surviving spouse inherit the unused portion of the deceased spouse’s exemption.² If the first spouse’s estate was worth $5 million, portability preserves the other $10 million of exemption for the survivor to use later. Without the election, that room disappears.

The election is made by filing a complete Form 706 by the nine-month deadline (plus any approved extension). If that deadline passes without a filing, Revenue Procedure 2022-32 offers a backup: estates that weren’t otherwise required to file can make a late portability election by submitting Form 706 within five years of the date of death.⁶ The five-year relief is available only when no return was otherwise required. If the estate exceeded the filing threshold, the normal deadline and extension rules control.

Getting More Time to File

Form 4768 buys an automatic six-month extension of the filing deadline, so long as it’s submitted on or before the original nine-month due date.⁷ No explanation is required. The filing deadline moves to 15 months after death.

Here’s the trap that catches new executors: the six-month filing extension does not extend the time to pay.⁷ The executor still has to estimate the tax owed and pay it by the original nine-month deadline. Interest and late-payment penalties start running immediately on any underpayment, whether or not the return itself has been filed.

Getting More Time to Pay

A separate payment extension is available when the estate genuinely cannot pay on time. Using the same Form 4768, the executor can request up to 12 months at a time, renewable for a total of up to 10 years, by demonstrating reasonable cause. The IRS grants these sparingly, and the reasonable-cause standard is real: qualifying situations include assets scattered across jurisdictions and not yet under the executor’s control, assets tied up in litigation, illiquid future-payment rights like annuities or royalties, or a genuine inability to cover the tax plus a reasonable allowance for the surviving spouse and dependents without borrowing at unreasonable rates. Interest continues to accrue on the unpaid balance even with an approved payment extension.⁸

Installments for Closely Held Businesses

Estates dominated by a family business have a dedicated relief provision. Section 6166 lets the estate tax attributable to a closely held business interest be paid in installments over up to 14 years: the first payment can be deferred up to five years, then the balance spread across up to ten annual installments.⁹ The business interest has to make up more than 35% of the adjusted gross estate, and the entity has to fit the statutory definition of closely held: a sole proprietorship, a partnership with 45 or fewer partners (or 20% ownership by the deceased), or a corporation with 45 or fewer shareholders (or 20% voting-stock ownership by the deceased). Passive assets don’t count toward the 35% threshold.

Penalties for Filing or Paying Late

Missing the deadline without an extension triggers two penalties that run in parallel.

The late-filing penalty is 5% of the unpaid tax for each month or partial month the return is overdue, capped at 25%.¹⁰ On a $2 million tax bill, that’s $100,000 per month, hitting the $500,000 cap at five months.

The late-payment penalty runs at 0.5% of the unpaid tax per month, also capped at 25%.¹¹ The rate drops to 0.25% when the return was filed on time and the executor has an installment agreement in place. It jumps to 1% if the IRS issues a levy notice and the tax remains unpaid after 10 days.

When both penalties apply in the same month, the filing penalty is reduced by the payment penalty for that overlap, so the combined charge is 5% per month rather than 5.5%. Once the return is filed and the filing penalty stops, the payment penalty continues on its own. Interest compounds daily on top of both, at the federal short-term rate plus three percentage points.¹²

Both penalties can be waived if the executor demonstrates reasonable cause, meaning circumstances beyond the executor’s control rather than unfamiliarity with the rules. Filing Form 4768 on time, even when the return and payment aren’t ready, is the simplest way to keep the filing penalty from ever starting.

State Estate Tax Deadlines Are Separate

The federal deadline doesn’t govern state filings. About a dozen states and the District of Columbia impose their own estate taxes, and a handful of states impose inheritance taxes on the recipients of bequests. State exemption thresholds are almost always far lower than the federal $15 million, some as low as $1 million, so an estate that owes nothing federally may still owe a state. Some states track the federal nine-month deadline; others set their own. Every state where the deceased lived or held real property is its own filing obligation with its own penalties, and those have to be checked separately.

1
Office of the Law Revision Counsel. 26 USC 6075 – Time for Filing Estate and Gift Tax Returns
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Internal Revenue Service. Frequently Asked Questions on Estate Taxes
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Internal Revenue Service. Whats New – Estate and Gift Tax
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Office of the Law Revision Counsel. 26 USC 2001 – Imposition and Rate of Tax
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Internal Revenue Service. Estate Tax
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Internal Revenue Service. Revenue Procedure 2022-32
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eCFR. 26 CFR 20.6081-1 – Extension of Time for Filing the Return
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Internal Revenue Service. Instructions for Form 4768
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Office of the Law Revision Counsel. 26 USC 6166 – Extension of Time for Payment of Estate Tax Where Estate Consists Largely of Interest in Closely Held Business
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Internal Revenue Service. Failure to File Penalty
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Internal Revenue Service. Topic No. 653, IRS Notices and Bills, Penalties and Interest Charges
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Internal Revenue Service. Quarterly Interest Rates