Estate Tax Calculator: The Complete 2026 Guide
How the federal estate tax works for 2025-2026: the 13.99-million-dollar exemption, the 40 percent top rate, portability, Form 706, state thresholds, and a worked example.
The federal estate tax touches a smaller share of estates than most people assume — but the ones it touches can owe up to 40 percent, and the paperwork deadline is measured in months, not years. An estate tax calculator turns the grim spreadsheet question — what would this estate owe, and by when? — into a number and a date. This guide explains what the tool computes, who genuinely needs it, and the exact 2025 and 2026 federal figures the math runs on: the 13.99-million-dollar exemption for 2025, the 40 percent top rate, and the portability election surviving spouses routinely miss. It also covers the state layer, where thresholds as low as one million dollars reach ordinary families. As always here, the output is an educational estimate, not professional advice.
CHAPTER 01What an Estate Tax Calculator Does
The estate tax is levied on the value of what a deceased person leaves behind, computed on Form 706. An estate tax calculator (/estate-tax-calculator.html) starts with the gross estate — real estate, accounts, businesses, retirement funds, and certain life insurance, valued as of the date of death — then subtracts deductions such as debts, funeral and administrative costs, charitable bequests, and assets left to a spouse. What remains is the taxable estate, added to any prior taxable gifts, compared against the exemption, and taxed at graduated rates from 18 to 40 percent on the excess.
The more useful job is comparative. Filing the election that preserves a deceased spouse's unused exemption can be worth millions, and the calculator shows that in one pass, the same way it shows what a charitable bequest or a lifetime gifting program does to the eventual bill. It is a planning instrument for the living, not merely an executor's chore.
CHAPTER 02Who Actually Needs One
For 2025 the federal exemption is 13.99 million dollars per person — 27.98 million for a married couple planning together — so only a small fraction of US deaths produce a federal estate tax bill. The tool still matters for four groups: families above those lines, executors deciding whether a Form 706 must be filed anyway, surviving spouses who need the portability election even when no tax is due, and residents of states with far lower thresholds than the federal one.
There is a second audience that surprises people: moderate estates holding a business, farmland, or a large life-insurance policy. Insurance payable to the estate or owned by the decedent counts in the gross estate, and a house in an expensive metro area plus retirement accounts can cross a state line's threshold long before the federal one. The calculator prices all of it before anyone commits to a plan.
CHAPTER 03The 2025-2026 Federal Figures the Math Runs On
Three numbers carry the federal math. First, the exemption: 13.99 million dollars per decedent for 2025, unified with the lifetime gift-tax exemption, meaning large lifetime gifts reduce what the estate can shelter. Second, the rate schedule: 18 percent at the bottom, rising to the famous 40 percent top rate on the excess above the exemption. Third, the unified credit table converts that schedule into the tentative tax the calculator applies.
For 2026, legislation enacted in July 2025 sets the basic exclusion at 15 million dollars per person, indexed for inflation in later years. Earlier planning built on a scheduled 2026 drop back toward 7 million dollars became obsolete — a useful reminder that estate figures are legislated and they change. Re-run the numbers against current law before acting on any plan drafted years earlier.
Deadlines are part of the math. Form 706 is due nine months after death, with a six-month filing extension available on Form 4768 — an extension of time to file, not to pay. Interest accrues on unpaid tax from the original due date, which is why the calculator's output should always be paired with the calendar, and why executors should calendar the date the week the estate opens rather than trusting memory.
CHAPTER 04Portability: The Election Surviving Spouses Miss
Portability lets a surviving spouse add the deceased spouse's unused exemption — the DSUE amount — to their own, so a couple can shelter the combined total without trusts. The catch is procedural: the election is made only on a timely filed Form 706, and that requirement applies even when the estate plainly owes no tax. An executor who files nothing to save paperwork can permanently forfeit millions of exemption for the survivor.
Some relief exists: estates not otherwise required to file can make a simplified late portability election, generally within about five years of death under IRS guidance. But the clean path is the original deadline, and this is precisely the decision an estate tax calculator informs — estimate the estate, check the unused exemption, and decide whether the 706 is worth filing. Usually it is.
CHAPTER 05State Estate Taxes: A Lower Line Than You Think
Roughly a dozen states plus the District of Columbia levy their own estate taxes, with thresholds far below the federal exemption. For 2025, Massachusetts taxed estates above 2 million dollars and Oregon above 1 million — lines that capture ordinary homes and retirement accounts, not just wealth — while New York sat near 7 million and Washington just above 2 million. There is no federal credit for state estate tax; the two systems stack.
A few wrinkles matter. Connecticut tracks the federal exemption, while most states set their own; New York penalizes estates just over its threshold with a cliff rather than a phase-in; and a handful of states levy inheritance taxes on recipients based on their relationship to the decedent. Property in several states can trigger more than one state filing. Any calculator run behind a planning decision should include the state layer, or the federal answer will be the smaller half of the bill.
CHAPTER 06A Worked Example With 2025 Numbers
A single decedent leaves a gross estate of 17.5 million dollars: a house, accounts, a business interest, and a paid-up life policy she owned. Debts, funeral, and administrative expenses total 500,000 dollars, so the taxable estate is 17 million, and she made no reportable lifetime gifts. The excess over the 13.99-million-dollar exemption is 3.01 million dollars, and the tentative tax on that excess is 1,149,800 — call it 1.15 million dollars due within nine months of death.
Now the comparative work the calculator exists for. Had she been married and left everything to her spouse, the unlimited marital deduction would have produced zero federal tax — but only a timely Form 706 would have preserved her unused 13.99 million for the survivor. Suppose instead that 2.5 million of the estate went to charity: the taxable estate falls to 14.5 million, and the federal bill drops to about 158,500 dollars. Run all three versions through our estate tax calculator (/estate-tax-calculator.html) and the planning decision makes itself.
CHAPTER 07What Counts, What Gets Deducted, and the Step-Up
The gross estate is broader than the probate estate. It includes worldwide assets, retirement accounts, jointly held property, certain trusts the decedent retained control over, and life insurance the decedent owned or held incidents of ownership in. Taxable gifts made beyond the annual exclusion are added back into the base. On the deduction side sit debts, last-illness and funeral costs, administration expenses, unlimited charitable bequests, and the unlimited marital deduction for a citizen spouse.
Every appreciated asset also receives a basis step-up at death — inherited property's cost basis generally resets to date-of-death value, erasing decades of built-in capital gain. That interacts directly with lifetime gifting, since gifts carry the donor's basis instead. Our capital gains tax calculator (/capital-gains-tax-calculator.html) covers the income-tax side of that trade-off: sell before death and owe gains tax, or hold and hand heirs a stepped-up basis. It is one of the genuinely consequential comparisons in the field.
CHAPTER 08Limits of Any Estate Tax Estimate
Be honest about scope. A calculator estimates federal and, if modeled, state tax on the values you enter. It cannot value a closely held business with marketability discounts, judge whether a family limited partnership holds up, predict a valuation audit, or interpret a will's formulas. The date-of-death values themselves — appraisals for real estate, art, and private company interests — are professional work with their own rules.
The figures in this guide reflect published 2025 parameters and the 15-million-dollar 2026 exclusion set by 2025 legislation, but estate law changes with Congress and with inflation adjustments, and state schedules move independently. For estates near any threshold, for blended families, or for anything involving a business, treat the calculator as the fast first draft and the estate attorney as the final one. That division of labor is the realistic best practice.
🔑 Key takeaways
- The 2025 federal exemption is 13.99 million dollars per person, unified with lifetime gifts; 2025 legislation sets 15 million for 2026, indexed thereafter.
- Rates run 18 to 40 percent on the excess over the exemption — the 40 percent headline rate applies only above that line.
- Portability of a deceased spouse's unused exemption requires a timely Form 706 even when no tax is due — the most commonly missed election in this field.
- Form 706 is due nine months after death; the six-month extension extends filing, not payment.
- State estate taxes bite far lower: for 2025, Massachusetts at 2 million dollars and Oregon at 1 million reach ordinary families.
- Every figure is an educational estimate on your inputs — valuations, audits, and document drafting belong with professionals.
❓ Frequently asked questions
Does a surviving spouse automatically receive the unused exemption?
No — portability must be elected on a timely filed Form 706, even when the estate owes nothing. A simplified late election exists for estates not otherwise required to file, generally within about five years of death, but the original deadline is the reliable path.
Is life insurance included in the taxable estate?
If the decedent owned the policy or held incidents of ownership, yes, at the death benefit's value. Policies owned by a genuinely independent irrevocable trust stay outside the estate, but whether a trust qualifies is a professional question, not a calculator question.
Do heirs pay income tax on what they inherit?
Generally not on the inheritance itself, and most assets receive a stepped-up basis, so later sales owe capital gains only on appreciation after death. Retirement accounts are a notable exception with income-in-respect rules; our capital gains tax calculator covers the gain side.
What is the deadline for filing Form 706?
Nine months after the date of death, with a six-month extension to file available on Form 4768. The extension does not extend time to pay, and interest runs on unpaid tax from the original due date.
Can a state tax an estate the federal government does not?
Yes. Roughly a dozen states plus DC levy estate taxes with much lower thresholds — for 2025, Massachusetts at 2 million dollars and Oregon at 1 million. The federal exemption is irrelevant at the state line, so model both layers.
How do lifetime gifts affect the estate calculation?
Taxable gifts beyond the annual exclusion are added back to the estate base, and the exemption they consumed is subtracted, so the estate cannot shelter the same dollars twice. Gifts within the 19,000-dollar annual exclusion never enter the calculation.
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