IRS Form 706 in 2026: Who Must File the Estate Tax Return

Form 706 is the United States Estate (and Generation-Skipping Transfer) Tax Return — the single most misunderstood filing in personal finance. Most people assume it only matters to the ultra-wealthy, and in one sense they are right: fewer than 1% of estates owe any federal estate tax. But “owing tax” and “must file” are two different questions, and the gap between them costs families real money every year.

In 2026 the federal estate tax filing threshold is $15,000,000 per person. An estate below that number generally owes nothing. Yet an executor may still need to file Form 706 to make the portability election, which locks in a deceased spouse’s unused exemption for the survivor. Miss that election and a married couple can forfeit millions in future tax protection.

What Form 706 Is and When It Is Required

Form 706 reports the value of everything a decedent owned or controlled at death, calculates the tentative estate tax, and applies the applicable exclusion amount. It is filed by the executor or personal representative. The IRS publishes the filing threshold for the year of death, and the number has moved a great deal over the last decade.

Year of Death	Filing Threshold (Basic Exclusion)
2021	$11,700,000
2022	$12,060,000
2023	$12,920,000
2024	$13,610,000
2025	$13,990,000
2026	$15,000,000

The test is not the net estate — it is the gross estate plus adjusted taxable gifts made after 1976. That means lifetime gifts that were large enough to require a gift tax return count toward the threshold, even though no gift tax was actually paid.

What Counts in the Gross Estate

Executors routinely underestimate the gross estate because they count only what the decedent “owned outright.” Federal law casts a wider net. Everything the decedent owned, controlled, or had an interest in at the moment of death is included at fair market value.

Real estate, including the primary residence, vacation property, and out-of-state land
Bank accounts, brokerage accounts, and cash
Stocks, bonds, mutual funds, and closely held business interests
Retirement accounts — IRAs, 401(k)s, and pensions
Life insurance proceeds, if the decedent owned the policy or held incidents of ownership
Vehicles, jewelry, art, and household tangible property
Certain gifts made within three years of death
Retained interests in trusts the decedent created

Life insurance is the line item that surprises families most. A policy the decedent owned is fully includible in the gross estate even though the death benefit is income-tax-free. Removing a policy from the estate generally requires an irrevocable life insurance trust or an outright ownership transfer well in advance of death.

Deadlines, Extensions, and Penalties

Form 706 is due nine months after the date of death. The deadline is firm, and it applies whether or not tax is owed. An automatic six-month extension of time to file is available by submitting Form 4768 before the original deadline — but the extension extends only the filing date. Any tax due must still be paid by the nine-month mark, and interest accrues on unpaid balances from that date.

Item	Rule for 2026
Original filing deadline	9 months after date of death
Extension of time to file	Automatic 6 months via Form 4768
Extension of time to pay	None automatic — interest accrues from the 9-month date
Late filing penalty	5% of unpaid tax per month, up to 25%
Top estate tax rate	40% on the taxable estate above the exclusion
Portability election	Must be made on a timely filed Form 706

The penalty structure is why an estate that owes nothing can still be penalized. If a return was required and is filed late, the failure-to-file penalty applies even with a zero balance due. Practitioners often file a protective Form 706 precisely to avoid that outcome and to preserve the portability election.

The Portability Election: Why Small Estates Still File

Portability allows a surviving spouse to use the deceased spouse’s unused exclusion amount — the “deceased spousal unused exclusion,” or DSUE. In 2026, a married couple that elects portability effectively commands roughly $30 million of combined exclusion. For most families that is more than enough to eliminate federal estate tax entirely.

But the election is not automatic. It can only be made on a timely filed Form 706. A surviving spouse whose late partner’s estate was well under the threshold may still need a Form 706 — not to pay tax, but to bank the unused exemption before it expires permanently.

Confirm the date of death and calculate the nine-month filing deadline.
Value every asset in the gross estate as of the date of death (or the alternate valuation date, if elected).
Total the gross estate and add adjusted taxable gifts made after 1976.
Compare the total to the filing threshold for the year of death.
Determine whether to elect portability, alternate valuation, or a qualified terminable interest property (QTIP) marital deduction.
Prepare and file Form 706 by the deadline, requesting Form 4768 if more time is needed.
After the IRS acknowledges the return, obtain the DSUE amount for the survivor’s records.

How Form 706 Interacts With Estate Planning

Two numbers do most of the work in federal estate tax planning: the exclusion amount and the value of the gross estate. Because the exclusion is applied at death, the planning question is really one of liquidity and inclusion — how much of the estate is exposed, and does the family have cash to pay the bill without fire-selling assets?

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Life insurance is the classic answer. A properly owned policy pays a death benefit outside of income tax and can be structured outside the gross estate, so it funds estate tax and administration costs without forcing a sale of the family business or the home. See our guide to life insurance and the estate tax for the ownership rules that matter.

Executors should also review the income-tax side of what they inherit. Heirs generally receive a step-up in basis at death — see step-up in basis in 2026 — while inherited retirement accounts follow the distribution rules covered in our required minimum distributions guide. State estate and inheritance taxes are a separate layer altogether; our inheritance tax guide covers the six states that levy one. And for the broader checklist, start with our 2026 estate planning checklist.

Common Filing Mistakes to Avoid

Assuming no filing is required because no tax is owed. Portability and protective filings both depend on submitting the return.
Valuing the wrong date. Assets are valued at death unless the executor validly elects the alternate valuation date six months later.
Forgetting life insurance. Proceeds from a policy the decedent owned belong in the gross estate.
Missing the nine-month deadline. Extensions help with filing, not with paying; interest accrues regardless.
Ignoring state-level obligations. A dozen states impose a separate estate or inheritance tax with different thresholds.

Frequently Asked Questions

Do I have to file Form 706 in 2026 if the estate is under $15 million?

Probably not for tax purposes, but you may still need to file to elect portability of a deceased spouse’s unused exclusion. The estate tax filing threshold for 2026 is $15,000,000 per person, so most estates owe nothing — yet a timely Form 706 remains the only way to preserve the survivor’s DSUE.

What is the deadline for Form 706?

Nine months after the date of death. An automatic six-month extension of time to file is available via Form 4768, but any tax owed remains due at the nine-month mark and interest accrues on the unpaid balance.

What is the penalty for filing Form 706 late?

The failure-to-file penalty is 5% of the unpaid tax per month, capped at 25%, plus interest. It applies even when no tax is ultimately owed if the return was required.

Does life insurance count toward the estate tax filing threshold?

Yes, if the decedent owned the policy or held incidents of ownership. The full death benefit is included in the gross estate, even though beneficiaries receive it income-tax-free. An irrevocable life insurance trust can remove the policy from the estate.

What is the portability election and why does it matter?

Portability lets a surviving spouse inherit the deceased spouse’s unused estate tax exclusion. For a 2026 married couple that is roughly $30 million of combined protection. The election must be made on a timely filed Form 706 — it is not automatic.

How much estate tax does a $20 million estate owe in 2026?

Assuming a single decedent with no prior gifts and the full $15 million exclusion available, the taxable estate is $5 million, taxed at up to 40% — roughly $2 million before deductions, credits, and planning strategies such as charitable or marital deductions.

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Plan Ahead With a Free Life Insurance Quote

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