IRS Form 706: The Federal Estate Tax Return Explained

The filing deadline is nine months after the date of death. An automatic six-month extension is available using Form 4768, but the extension is for filing only — estimated tax must be paid by the original due date. The executor or personal representative of the estate is responsible for filing.

Even when no tax is owed, Form 706 may need to be filed to elect portability; the ability to transfer any unused estate tax exemption to the surviving spouse.

Key Sections Explained

• Part 1; Decedent and Executor: Basic information about the deceased, the executor, and the attorney handling the estate.
• Part 2; Tax Computation: The core calculation that starts with the gross estate, subtracts deductions, applies the unified credit, and determines the net estate tax due.
• Schedules A through I; Asset Schedules: Each schedule covers a different category of assets: real estate (Schedule A), stocks and bonds (Schedule B), mortgages and notes (Schedule C), insurance on the decedent's life (Schedule D), jointly owned property (Schedule E), other miscellaneous property (Schedule F), transfers during the decedent's life (Schedule G), powers of appointment (Schedule H), and annuities (Schedule I).
• Schedule J-L; Deductions: Funeral and administration expenses (Schedule J), debts of the decedent (Schedule K), and net losses during administration (Schedule L).
• Schedule M; Marital Deduction: Property passing to the surviving spouse, which qualifies for the unlimited marital deduction. This deduction can eliminate estate tax entirely at the first spouse's death.
• Schedule O; Charitable Deduction: Bequests to qualifying charities, which are fully deductible.
• Portability Election: Part 6 of the form allows the estate to transfer any unused exemption (the Deceased Spousal Unused Exclusion Amount, or DSUE) to the surviving spouse.

Common Mistakes

Failing to file for portability is one of the most consequential oversights in estate planning. If the first spouse to die has an estate below the exemption threshold, no estate tax is due; but the unused exemption is lost unless Form 706 is filed to elect portability. Many families skip the filing because no tax is owed, not realizing they're forfeiting millions in future exemption. The IRS has granted late portability election relief in many cases, but it requires a private letter ruling or meeting specific revenue procedure requirements.

Undervaluing assets; particularly closely held businesses, real estate, and art; is a frequent audit trigger. The IRS has specialized appraisers and economists who review valuations on estate tax returns. Discounts for lack of marketability and minority interests are legitimate but must be well-supported by qualified appraisals. Aggressive discounts without adequate documentation invite challenge.

Missing the stepped-up basis opportunity is a planning failure rather than a filing error. When someone dies, the tax basis of their assets is "stepped up" to fair market value at the date of death. This means unrealized capital gains accumulated during the decedent's lifetime are permanently eliminated. Not accounting for this benefit, or worse, inadvertently structuring ownership to avoid it, can cost heirs significant capital gains tax.

Not coordinating the estate return with income tax returns can lead to errors. Deductions can sometimes be taken on either the estate tax return (Form 706) or the estate's income tax return (Form 1041), but not both. The executor must make strategic decisions about where to claim deductions for maximum benefit.

Recent Changes

The most pressing issue is the scheduled sunset of the TCJA's doubled exemption after 2025. Unless Congress acts, the exemption will revert from approximately $14 million per person to roughly $7 million (indexed for inflation). This change would dramatically increase the number of taxable estates — potentially from 4,000 per year to 30,000 or more.

In anticipation of the sunset, the IRS issued final regulations confirming that gifts made under the current higher exemption will not be "clawed back" if the exemption later decreases. This anti-clawback rule has prompted a wave of estate planning activity, with wealthy individuals making large gifts to take advantage of the higher exemption before it potentially drops.

The IRS has also expanded late portability election relief, issuing Revenue Procedure 2022-32, which allows estates to file a late portability election within five years of the decedent's death (up from two years). This has provided relief to thousands of surviving spouses whose estates failed to file Form 706 on time.

There continues to be legislative interest in modifying the stepped-up basis rules. Some proposals have called for eliminating the step-up or replacing it with carryover basis (where heirs take the decedent's original basis). While no changes have been enacted, this remains an active area of policy debate.

For more information, see the official IRS page: About Form 706.

This article is educational and does not constitute tax advice. Consult a qualified tax professional for guidance specific to your situation.