IRS Form 706: A Comprehensive Guide to Completing the Estate Tax Return for U.S. Citizens and Residents

Form 706 is the IRS estate tax return filed for the estates of U.S. citizens and permanent residents. It reports the estate’s assets, calculates any federal estate tax owed, and serves two additional functions that often require filing even when no tax is due: preserving the portability election for a surviving spouse and allocating the generation-skipping transfer (GST) tax exemption.

Under current law, the federal estate tax exclusion is $15,000,000 per person, indexed annually for inflation. Most estates fall well below this threshold, but filing requirements extend beyond estates with a tax liability. Below, we walk through who must file, what the return covers, and how to complete it.

What is IRS Form 706?

IRS Form 706 is the United States Estate (and Generation-Skipping Transfer) Tax Return. Executors file it on behalf of a deceased U.S. citizen’s or permanent resident’s estate. Despite the name, the return is not filed exclusively to pay estate tax. Rather, it serves three distinct purposes.

1. Calculating Federal Estate Tax

Form 706 reports the fair market value of all assets in the gross estate and determines whether federal estate tax is owed. The return is required when the gross estate, combined with adjusted taxable gifts made during the decedent’s lifetime, equals or exceeds the applicable exclusion amount for the year of death.

2. Electing Portability of the Unused Exclusion

A surviving spouse can claim the deceased spouse’s unused estate tax exclusion (DSUE) by filing Form 706, even if the estate owes no tax. Without this election, the unused exclusion is forfeited permanently. Late portability elections are available in certain circumstances, which are covered below.

3. Allocating the GST Exemption

Form 706 is also used to report and allocate the GST tax exemption. Proper allocation protects transfers to grandchildren and other skip persons from generation-skipping transfer tax and is a key step in multigenerational estate planning.

Who Must File Form 706?

Form 706 is required when the decedent’s gross estate, combined with adjusted taxable gifts made during their lifetime, equals or exceeds the applicable exclusion amount for the year of death.

For decedents dying in 2026 and later years, the exclusion is $15,000,000, set permanently under the One Big Beautiful Bill Act and adjusted annually for inflation. For deaths occurring in 2025, the exclusion was $13,990,000 per Rev. Proc. 2024-40.

Even when the estate falls below the taxable threshold, filing may still be required or desired. The most common reason is the portability election.

What Is the Portability Election?

A surviving spouse may elect to use the deceased spouse’s unused exclusion amount by filing Form 706. This election does not happen automatically. Without a filed return, the DSUE is lost.

Under Rev. Proc. 2022-32, eligible estates have up to five years from the date of death to file a late portability return without requesting a private letter ruling. This extended window replaced the prior two-year deadline under Rev. Proc. 2017-34 and gives surviving spouses meaningful time to evaluate the election. Form 706 applies only to U.S. citizens and permanent residents. The estates of nonresident aliens are governed by different rules and file Form 706-NA instead.

Key Deadlines and Filing Requirements

Form 706 is due nine months after the decedent’s date of death. For example, if the decedent died on March 15, 2026, the return is due December 15, 2026.

Extension of Time to File

Executors may request an automatic six-month extension by filing Form 4768 before the original nine-month deadline. The extension applies to the filing deadline only. Estate tax owed is still due by the original nine-month date. Amounts not paid by that date accrue interest and may be subject to late-payment penalties.

Elections That Require a Timely Filed Return

Certain elections available on Form 706 must be made on a timely filed return and cannot be made after the deadline, even with an extension. These include the alternate valuation election under IRC §2032, QTIP elections, and GST exemption allocations. Executors should work with counsel early to identify which elections apply and ensure the return is filed on time.

How to Complete IRS Form 706 (Step-by-Step Guide)

Completing Form 706 requires methodical documentation of estate assets, deductions, and elections. The steps below follow the return’s structure from gathering documents through filing.

Step 1: Gather Essential Documents

Before completing any schedules, collect the following: the decedent’s Social Security number, date of death, prior taxable gift history, a complete inventory of assets and their date-of-death values, outstanding debts and liabilities, and information on any trusts the decedent controlled or held interests in. Accurate date-of-death valuations are foundational to the entire return.

Step 2: Inventory and Value Estate Assets

Form 706 uses a series of asset schedules (Schedules A through I) to categorize and report all property included in the gross estate. This includes real estate, securities, business interests, retirement accounts, life insurance proceeds, jointly held property, and certain transferred assets. Each category requires fair market value as of the date of death, or the alternate valuation date if elected.

Step 3: Calculate the Gross Estate

The gross estate is the total of all asset schedule values. It includes not only assets the decedent owned outright but also certain transferred assets, assets held in trust, and life insurance proceeds payable to the estate. Common valuation errors at this stage can affect the entire return.

Not all inclusions are obvious. Life insurance proceeds are included in the gross estate when the decedent owned the policy at death, even if payable directly to a named beneficiary. Assets held in revocable trusts are fully includible. Retirement accounts, annuities, and jointly held property are included at the decedent’s proportionate share. Certain assets transferred within three years of death may also be pulled back into the gross estate under IRC §2035. Executors frequently underestimate the gross estate by missing these categories, which is one of the most common triggers for IRS adjustment.

Step 4: Apply Allowable Deductions

Form 706 allows deductions that reduce the gross estate to arrive at the taxable estate. Key deductions include funeral and estate administration expenses (Schedule J), the decedent’s outstanding debts (Schedule K), the marital deduction for assets passing to a surviving spouse (Schedule M), and charitable bequests (Schedule O). The marital deduction is unlimited for qualifying transfers to a U.S. citizen spouse. QTIP and marital deduction elections are irrevocable and permanently affect the taxable estate, making accuracy at this stage critical.

Step 5: Determine the Taxable Estate and Calculate Tax

The taxable estate equals the gross estate minus allowable deductions. Adjusted taxable gifts made during the decedent’s lifetime are then added to arrive at the tax base. The applicable exclusion amount is applied as a credit against the computed tax. For 2026 and later years, the exclusion is $15,000,000 per person under the One Big Beautiful Bill Act.

Step 6: Complete Elections and File

Before filing, identify and complete any applicable elections: the portability election (Part 6), QTIP election for marital deduction trusts, and GST exemption allocations. File the completed return with payment of any tax owed by the nine-month deadline, or by the extended deadline if Form 4768 was timely filed.

Common Mistakes to Avoid

Handling Form 706 can be a complex process, especially when large estates or multiple beneficiaries are involved. Here are some common mistakes to watch out for:

1. Skipping the portability election: Many executors file Form 706 only when estate tax is owed. If the decedent had a surviving spouse, a portability election should almost always be evaluated, even for estates well below the taxable threshold. Without a filed return, the DSUE is forfeited permanently.
2. Undervaluing or overvaluing assets: All assets must be reported at fair market value as of the date of death. Incorrect valuations can trigger IRS scrutiny or result in an overpayment of estate taxes.
3. Missing deadlines: Filing late can result in significant penalties and interest. Certain elections, including portability, QTIP, and GST allocations, must be made on a timely filed return and cannot be corrected after the fact.
4. Overlooking deductions: Administration expenses including executor fees, attorney fees, and appraisal costs are deductible and frequently underreported.
5. Missing QTIP and GST elections: These elections must be made on the original return. Extensions do not extend election deadlines.
6. Choosing the wrong form: Executors filing for a nonresident alien decedent must use Form 706-NA, not Form 706. The two returns apply to different categories of decedents and carry different thresholds and rules. Confirming residency status before filing avoids delays and penalties.
7. Failing to request an estate tax closing letter: An IRS estate tax closing letter (Letter 627) confirms that the return has been reviewed and accepted. Without it, distributing estate assets and formally closing the estate can be delayed. Executors should request this letter after the return is processed. As of May 2025, the user fee to request a closing letter is $56.

Completing Form 706 correctly can be complex, especially given the stakes involved with estate taxes and IRS penalties. Our estate tax attorneys at Evolution Tax and Legal handle all aspects of the estate tax filing process, from accurate asset valuations to meeting deadlines and ensuring IRS compliance. Contact us to schedule a consultation.

What Happens After You File Form 706?

Filing Form 706 does not immediately close the estate’s federal tax obligations. The IRS typically takes a year or more to process the return, and complex returns involving closely held businesses, large real estate holdings, or significant valuation discounts are more likely to be selected for audit. Inadequate appraisals, large deductions, and discrepancies between the reported estate value and third-party data are the most common audit triggers.

The Estate Tax Closing Letter

After reviewing the return, the IRS issues an estate tax closing letter (Letter 627) confirming that the return has been accepted and the estate tax liability has been satisfied. This letter is essential for formally closing the estate and distributing assets to beneficiaries. Effective May 21, 2025, the IRS reduced the user fee to request a closing letter from $67 to $56 per Treasury Decision 10031. Executors should request this letter proactively after the return is processed rather than waiting for it to arrive automatically.

Discharge from Personal Liability

An executor who distributes estate assets before the estate tax is fully resolved may be held personally liable for unpaid tax. To protect against this, executors can request discharge from personal liability under IRC §2204 by submitting a written request to the IRS after filing Form 706. Once the IRS issues the discharge, the executor is released from personal liability for any deficiency later discovered, shifting the risk to the estate or its beneficiaries.

Managing the post-filing process, from responding to IRS inquiries to securing your closing letter, is part of what our team at Evolution Tax and Legal handles on behalf of estate administrators. If you are navigating an estate tax matter, contact us to schedule a consultation.

Frequently Asked Questions (FAQs)

Do I need to file Form 706 if the estate is below the exemption amount?

Not necessarily, but filing may still be required or advisable. The most common reason to file when no tax is owed is to elect portability of the deceased spouse’s unused exclusion amount. Without a filed return, that election is forfeited permanently.

What is the difference between IRS Form 706 and Form 706-NA?

Form 706 is filed for the estates of U.S. citizens and permanent residents and covers worldwide assets. Form 706-NA is filed for the estates of nonresident alien decedents and covers only U.S.-situs assets. The applicable exclusion amounts and filing rules differ significantly between the two returns. For 2026, the federal exclusion for U.S. citizens and residents is $15,000,000; the exclusion for nonresident aliens is $60,000.

Can I amend Form 706 after filing?

Yes. A supplemental Form 706 can be filed to correct errors or report additional information discovered after the original return was submitted. However, certain elections made on the original return, including the QTIP election and GST exemption allocations, are generally irrevocable and cannot be changed on an amended return.

What happens if I miss the filing deadline?

Late filing can result in penalties of up to 25% of the unpaid tax, plus interest accruing from the original due date. More significantly, missing the deadline can permanently forfeit the portability election, which may cost a surviving spouse millions in lost exemption on a future estate.

Does my state have its own estate tax?

California does not impose a state estate tax. However, ten states and the District of Columbia maintain independent estate tax systems with exemption thresholds significantly below the federal $15,000,000. These include Connecticut ($9,100,000), Massachusetts ($2,000,000), Minnesota and Washington ($3,000,000 each), Hawaii ($3,500,000), Vermont ($5,000,000), New York (approximately $5,000,000, adjusted annually for inflation), Illinois, Oregon, and the District of Columbia ($1,545,800, adjusted annually for inflation). Iowa repealed its estate and inheritance tax effective January 1, 2025.

If the decedent owned real estate or held business interests in multiple states, additional estate tax returns may be required in each state where the property was located. State estate tax rules are separate from federal Form 706 and require independent analysis.

How do I pay estate taxes owed with Form 706?

Estate tax payments can be made by check or electronically through the Electronic Federal Tax Payment System (EFTPS). Payment is due by the nine-month deadline regardless of whether a filing extension has been requested. Estates with closely held business interests may qualify to pay tax in installments under IRC §6166, which allows deferral of a portion of the estate tax for up to fourteen years.

If your estate or a loved one’s estate may require Form 706, working with an experienced estate tax attorney and CPA from the start reduces errors, protects elections, and ensures deadlines are met. Contact Evolution Tax and Legal to schedule a consultation.

This article is for informational purposes only and does not constitute legal or tax advice. Tax laws and regulations change frequently and may affect the accuracy of this information. Consult a qualified tax attorney or CPA before making any decisions based on the content of this article.