Guides
Form 706 Explained: The Federal Estate Tax Return
Form 706 is the United States Estate (and Generation-Skipping Transfer) Tax Return, the return an executor files to report a decedent’s gross estate, calculate any federal estate tax, and preserve a surviving spouse’s unused exemption. For 2026 deaths, the return is generally required only when the gross estate plus lifetime taxable gifts exceeds $15 million, though estates below that line still file to elect portability. The return is due nine months after death.
The form matters far beyond the small share of estates that owe tax. Filing Form 706 is the only way to transfer a deceased spouse’s leftover exemption (the DSUE amount) to the survivor, and missing that election can quietly cost a family millions of dollars of exemption on the second death.
Who must file Form 706 in 2026?
An executor must file Form 706 when a U.S. citizen or resident dies in 2026 and the gross estate, plus adjusted taxable gifts and any specific gift-tax exemption used, exceeds $15,000,000. A return is also required, regardless of estate size, whenever the executor elects to transfer the deceased spousal unused exclusion (DSUE) to the surviving spouse.
The $15 million figure comes from the One Big Beautiful Bill Act (OBBBA), which set the basic exclusion at $15,000,000 per person for 2026 and made that level permanent, indexed for inflation after 2026. For a married couple, that can shelter up to $30,000,000 in combined transfers when portability is used correctly.
Two filing triggers exist, and they operate independently:
- Taxable-estate trigger: gross estate plus adjusted taxable gifts exceeds the exclusion for the year of death ($15,000,000 in 2026, $13,990,000 in 2025).
- Portability trigger: the estate elects to pass unused exclusion to a surviving spouse, even when the estate is far below the threshold and owes no tax.
Nonresident non-citizens who owned U.S.-situated property generally file Form 706-NA, a separate return, not Form 706.
What is the Form 706 filing deadline?
Form 706 is due nine months after the decedent’s date of death. An executor can get an automatic six-month filing extension by submitting Form 4768 before that original deadline, which pushes the paperwork date out to roughly 15 months after death.
The extension covers filing, not payment. Any estate tax owed is still due at the original nine-month mark, and interest runs from that date on unpaid amounts. Executors who expect tax due often pay an estimate with Form 4768 to stop interest, then reconcile when the completed return is filed.
Some elections must be made on a timely filed return and cannot be added later, even with an extension. These include the alternate valuation election under IRC Section 2032, the qualified terminable interest property (QTIP) marital election, and allocations of the generation-skipping transfer (GST) exemption. Late filing can trigger penalties of up to 25% of the unpaid tax under the failure-to-file rules, on top of interest.
How the estate tax is calculated
The federal estate tax uses a unified rate schedule (Table A on the form) that climbs from 18% on the first bracket to a top rate of 40% on taxable amounts above $1,000,000. Because the exclusion shelters the first $15 million in 2026, the 40% rate is effectively the only rate most taxable estates ever feel at the margin.
The calculation stacks lifetime and death transfers together, then backs out credits. In simplified order:
- Gross estate: fair market value at death of all property the decedent owned or controlled (real estate, investments, business interests, retirement accounts, life insurance the decedent owned, and certain gifts).
- Deductions: debts, funeral and administration expenses, the unlimited marital deduction for property passing to a citizen spouse, and the charitable deduction.
- Taxable estate: gross estate minus deductions.
- Add adjusted taxable gifts: post-1976 lifetime taxable gifts are added back to set the tax bracket.
- Tentative tax and unified credit: apply Table A rates, then subtract the applicable credit tied to the $15 million exclusion.
| Item | 2025 | 2026 |
|---|---|---|
| Basic exclusion amount | $13,990,000 | $15,000,000 |
| Top marginal rate | 40% | 40% |
| Annual gift exclusion (per recipient) | $19,000 | $19,000 (indexed) |
| Combined exclusion, married couple (via portability) | up to $27,980,000 | up to $30,000,000 |
| Filing deadline after death | 9 months | 9 months |
Because the exclusion is expressed as a dollar amount but applied through a “unified credit,” the form works in credit terms internally. The practical takeaway is unchanged: transfers up to the exclusion pay no federal estate tax, and the excess is taxed at up to 40%.
The portability (DSUE) election
Portability lets a surviving spouse add the deceased spouse’s unused exclusion (the DSUE amount) to their own. The only way to elect it is to file a complete and timely Form 706 for the first spouse to die, even when that estate is small and owes nothing. Without the filing, the unused exemption is lost.
Consider a spouse who dies in 2026 using $3,000,000 of their $15,000,000 exclusion. If the executor files Form 706 and elects portability, the $12,000,000 of unused exclusion transfers to the survivor, giving the survivor up to $27,000,000 of combined exclusion (their own $15,000,000 plus the $12,000,000 DSUE). Skip the filing, and the survivor keeps only their own exclusion.
For estates that are not otherwise required to file, Rev. Proc. 2022-32 provides a simplified extension: the executor may file a portability-only Form 706 on or before the fifth anniversary of the decedent’s death, without a private letter ruling. The return must state at the top that it is “Filed Pursuant to Rev. Proc. 2022-32 to Elect Portability under section 2010(c)(5)(A).” This relief applies only when a return was not otherwise required, the decedent died after 2010, was a U.S. citizen or resident, and was survived by a spouse.
Portability applies to the estate tax exclusion only. It does not carry over the GST exemption, which must be allocated separately and generally cannot be recovered after the deadline. Couples with generation-skipping goals often still use credit-shelter trusts rather than relying on portability alone.
What Form 706 requires you to attach
Form 706 is document-heavy because the IRS values the estate from source records, not estimates. The core schedules cover assets by category (real estate on Schedule A, stocks and bonds on Schedule B, and so on) and deductions by type.
Common attachments include:
- Certified death certificate and, where applicable, letters testamentary.
- Appraisals for real estate, closely held business interests, and hard-to-value assets.
- Copies of the will and any trust instruments.
- Account statements and date-of-death valuations for financial assets.
- Life insurance details on Form 712 for policies included in the estate.
For portability-only filings under the simplified method, the instructions allow estimated values for property that qualifies for the marital or charitable deduction, which reduces the appraisal burden. The estate must still report enough to establish the DSUE amount accurately.
Frequently asked questions
Does every estate have to file Form 706?
No. For 2026 deaths, filing is generally required only when the gross estate plus adjusted taxable gifts exceeds $15,000,000. Most estates fall well below that line and owe no federal estate tax. The main reason smaller estates file is to elect portability of the deceased spouse’s unused exclusion, which requires a timely Form 706 even when no tax is due.
What happens if Form 706 is filed late?
A late return can draw a failure-to-file penalty of up to 25% of the unpaid tax, plus interest running from the original nine-month due date. The larger risk is often non-monetary: certain elections, including alternate valuation and QTIP, are lost if the return is not timely, and a missed portability election can forfeit millions in exemption for the surviving spouse.
Can the Form 706 deadline be extended?
Yes, in part. Filing Form 4768 before the nine-month deadline grants an automatic six-month extension to file. Payment is not extended, so estate tax is still due at nine months and interest accrues on any unpaid balance. For portability-only returns that were not otherwise required, Rev. Proc. 2022-32 allows filing up to five years after death.
How much can a married couple shield from estate tax in 2026?
Up to $30,000,000, in many cases. Each spouse has a $15,000,000 exclusion in 2026 under OBBBA. When the first spouse’s executor files Form 706 and elects portability, the survivor may combine both exclusions. The exact amount depends on how much exclusion the first spouse used during life and at death.
Is Form 706 the same as an estate income tax return?
No. Form 706 reports the value of the estate for the one-time transfer (estate) tax. Income earned by the estate after death, such as interest, dividends, or rent during administration, is reported separately on Form 1041, the fiduciary income tax return. Many estates file Form 1041 without ever needing Form 706.
What is the top federal estate tax rate?
The top federal estate tax rate is 40%. The unified schedule technically starts at 18% and rises through several brackets, but because the $15,000,000 exclusion for 2026 absorbs the lower brackets, any taxable estate reaches the 40% marginal rate on amounts above the exclusion.
For a broader data view of who actually owes these taxes and how much the transfer tax raises, see The Estate and Gift Tax Report 2026. Executors weighing the basis consequences of inherited assets may also want to review Section 1014 step-up in basis, which resets an asset’s cost basis to fair market value at death. Estates administering ongoing income should compare requirements against the Schedule K-1 rules for beneficiaries and the cost basis fundamentals that carry into any later sale.
Reviewed by The Ledgerism Editorial Team. Last reviewed: July 2026.