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Federal Estate Tax Calculator

Estimate federal estate tax owed on an estate above the lifetime exemption amount.

Result

Taxable Estate
$1,010,000.00
Estimated Federal Estate Tax
$404,000.00

Uses the 2025 federal lifetime exemption ($13.99M per individual, effectively doubled for married couples with proper planning). The top federal estate tax rate is 40% on amounts above the exemption - this is a simplified flat-rate estimate; the actual estate tax uses a graduated bracket structure below the top rate for amounts just over the exemption.

About the Estate Tax Calculator

This calculator estimates federal estate tax owed on an estate that exceeds the lifetime gift and estate tax exemption. It is intended for high-net-worth individuals or estate planners assessing rough estate tax exposure at death.

How It Works

You enter the gross estate value and any lifetime gift exemption already used during your life. The calculator subtracts prior gifts from the 2025 lifetime exemption to find your remaining exemption, subtracts that remaining exemption from the estate value to find the taxable estate, and applies a flat 40% top federal estate tax rate to that taxable amount.

remainingExemption = max($13,990,000 - priorGiftsUsed, 0); taxableEstate = max(estateValue - remainingExemption, 0); estateTax = taxableEstate x 40%.

Formula & Methodology

The federal estate and gift tax share one unified lifetime exemption, so any of it used through lifetime gifts reduces what remains available at death. The calculator models this directly: it subtracts prior gifts used from the full 2025 exemption of $13,990,000 to get the remaining exemption, then subtracts that remaining amount from the gross estate value to find the taxable estate. The taxable estate is then taxed at a flat 40% rate, representing the top federal estate tax bracket, rather than modeling the graduated brackets that apply just above the exemption threshold.

Examples

Estate above the exemption with no prior gifts

An estate valued at $15,000,000 with no prior lifetime gifts has a remaining exemption of the full $13,990,000, producing a taxable estate of $1,010,000 and an estimated federal estate tax of $1,010,000 x 40% = $404,000.

Estate with exemption partially used by lifetime gifts

An estate valued at $20,000,000 where $5,000,000 of the lifetime exemption was already used through prior gifts leaves a remaining exemption of $8,990,000, producing a taxable estate of $11,010,000 and an estimated tax of $11,010,000 x 40% = $4,404,000.

Advantages

  • Accounts directly for lifetime gifts already made, reflecting the real unified exemption rather than treating estate and gift taxes as unrelated.
  • Gives a fast order-of-magnitude estimate for estates well above the exemption without requiring a full estate tax return calculation.
  • Makes clear how much of the exemption remains available after prior lifetime giving, useful for ongoing estate planning conversations.

Common Mistakes

  • Forgetting that lifetime gifts above the annual exclusion reduce the same exemption used at death, and treating the two as separate limits.
  • Assuming the flat 40% rate applies from the very first dollar of the estate rather than only to the amount above the exemption.
  • Not accounting for spousal portability, which can effectively double the exemption available to a married couple with proper planning, something this single-individual estimate does not include.

Edge Cases to Watch For

  • If prior gifts used equal or exceed the full $13,990,000 exemption, no exemption remains and the entire estate value above zero is taxed at 40%.
  • If the estate value is below the remaining exemption, the taxable estate and tax are both zero.
  • The calculator applies a flat 40% rate to the entire taxable estate rather than the graduated bracket structure that technically applies to amounts just above the exemption, so it is a simplified upper-bound-style estimate near the exemption threshold.
  • This estimate does not model the effectively doubled exemption available to married couples through portability, since the exemption entered applies to a single individual only.

Common Use Cases

  • Individuals with estates well above the exemption threshold estimating rough federal estate tax exposure.
  • Estate planners illustrating how lifetime gifting interacts with the exemption available at death.
  • Financial advisors giving clients a starting point for estate tax discussions before detailed planning with an attorney.
Written & fact-checked by the Calculateus TeamLast updated August 5, 2026How we verify our formulas

Frequently asked questions

Why does the estate tax exemption matter for gifts made during your lifetime too?

The federal gift and estate tax share a single unified lifetime exemption - large gifts made during your life that exceed the annual gift tax exclusion count against and reduce the same exemption amount available at death, which is why estate planning often considers lifetime giving and eventual estate transfer together as one combined tax strategy rather than two separate issues.

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Conclusion

This calculator translates the unified lifetime exemption and top estate tax rate into a quick estimate of federal estate tax exposure. Because it uses a flat 40% rate and does not model spousal portability or the graduated brackets near the exemption threshold, it works best as a starting figure rather than a precise final calculation.

References