Detailed Answer

1) Final individual income tax return (decedent’s last Form 1040)

The decedent’s final individual income tax return (Form 1040) covers income earned up to the date of death. The personal representative or executor generally files that return on behalf of the decedent. This is separate from any estate-level return. For guidance from the IRS, see: IRS: Final return for a person who died.

2) Federal fiduciary income tax return (Form 1041) — when it is required

The estate may need to file Form 1041 (U.S. Income Tax Return for Estates and Trusts) if any of these apply during the estate’s tax year:

• The estate has gross income of $600 or more for the tax year; or
• Any beneficiary is a nonresident alien.

That means even if the estate made no distributions to beneficiaries, the estate must file Form 1041 if it received reportable income (for example, bank interest, dividends, rent, capital gains from sales of estate assets, or other income) totaling $600 or more in a tax year. If the estate received no income and no beneficiary is a nonresident alien, you generally do not need to file Form 1041.

See IRS guidance: About Form 1041.

3) Federal estate tax return (Form 706) — when it is required

Form 706 (United States Estate (and Generation-Skipping Transfer) Tax Return) is different: it reports the value of the decedent’s gross estate and computes any federal estate tax due. Whether you must file Form 706 depends on the gross estate value (plus certain prior taxable gifts) relative to the federal estate tax exemption in effect for the year of death. If the gross estate is below the federal exemption, no federal estate tax will be due and often no Form 706 is required. If the estate’s gross value exceeds the federal filing threshold, Form 706 must be filed (generally within nine months of death, unless an extension is obtained).

For current federal estate tax filing rules and deadlines, see: About Form 706. Because the federal exemption changes over time, check the IRS site for the year of death.

4) Washington state estate tax

Washington State has its own estate tax with filing thresholds and rules that are independent of the federal estate tax. Even if no federal estate tax return is required, a Washington estate tax return may be required if the estate’s value meets or exceeds Washington’s threshold. For Washington-specific filing details, forms, and thresholds, see the Washington State Department of Revenue: Washington DOR — Estate Tax, and the Washington statutes on estate tax: RCW Chapter 83.100.

5) Practical examples

• Example A — No income and no distributions: If the estate holds only non-income-bearing assets (for example, an unreleased safe-deposit box with personal papers) and truly earns zero income in the year, and no beneficiaries are nonresident aliens, you generally do not have to file Form 1041.
• Example B — Interest or dividends but no distributions: If the estate’s bank account earns $750 of interest in the year and the estate retains the funds (no distributions), Form 1041 must be filed because gross income exceeds $600.
• Example C — Large estate but no federal estate tax: The gross estate might be above Washington’s estate tax threshold even if it is below the federal exemption — in that case you may need to file a Washington estate tax return even though no federal estate tax return (Form 706) is required.

6) Filing timelines and other filing particulars

• Form 1041 deadlines: Calendar-year estates generally file Form 1041 by the same date that individual returns are due (usually April 15 of the year following the tax year). See the Form 1041 instructions on the IRS website for exact deadlines and extension procedures: Form 1041.
• Form 706 deadline: Generally due nine months after the date of death; a six-month extension can be requested. See: Form 706.
• State deadlines: Washington’s estate tax return deadlines and payment rules differ from federal deadlines — consult the Washington DOR: Washington DOR — Estate Tax.

Practical steps to determine whether to file

1. Gather records: bank statements, brokerage statements, closing statements for sold property, and records of income received after death.
2. Calculate estate gross income for the year(s) after death (interest, dividends, rental income, capital gains, etc.). If gross income for any estate tax year is $600 or more, plan to file Form 1041.
3. Confirm beneficiary residency: if any beneficiary is a nonresident alien, file Form 1041 regardless of the $600 rule.
4. Determine gross estate value for federal and Washington estate tax purposes. If values approach known thresholds, consult the IRS and Washington DOR guidance (and consider professional advice).
5. Keep accurate records and file timely. If you need an extension, file the appropriate IRS or state extension forms before the deadline.

Helpful Hints

• Remember the decedent’s final Form 1040 covers income to date of death; post-death income belongs to the estate and may trigger Form 1041.
• Small amounts of interest or dividends can trigger a filing if they push estate income over $600 in a tax year.
• Washington has no personal income tax, but it does have an estate tax — that can create filing obligations even when no federal estate tax return is required. See Washington DOR: https://dor.wa.gov/taxes-rates/other-taxes/estate-tax.
• If you think Form 1041 is required because of income but distributions were not made, you still must report and either pay tax at the estate level or allocate income to beneficiaries (via Schedule K-1) if distributions are later made.
• When in doubt, consult a qualified tax professional or probate attorney — filing mistakes can cause penalties or interest.