Illinois Estate Tax Calculator

Pri Geens

Pri Geens

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Illinois Estate Tax Calculator

Estimate the combined federal and Illinois estate tax on an Illinois decedent’s estate. Illinois is one of the few states with its own estate tax: a decoupled tax with a $4,000,000 exemption that acts as a cliff — once the estate exceeds $4,000,000 the entire Illinois taxable estate is taxed at graduated rates from 0.8% to 16% (Form IL-706). Illinois has no inheritance tax and no gift tax. Three modes: estimate the tax, test a larger estate, or solve for the years of gifting needed to reach zero. Fields marked * are required; Calculate names any left empty.

Illinois rules this calculator enforces: state estate tax YES — decoupled from federal, $4,000,000 exemption acting as a CLIFF (estates at or below $4,000,000 owe $0; above it the ENTIRE Illinois taxable estate is taxed at graduated 0.8% to 16% rates with no deduction for the exemption), filed on Form IL-706 (rate schedule VERIFY); no inheritance tax; no gift tax; common-law (equitable distribution) state, not community property; spousal elective share 1/3 of the estate if the decedent left descendants else 1/2 (755 ILCS 5/2-8; VERIFY); small-estate affidavit where personal property is $100,000 or less (755 ILCS 5/25-1; VERIFY); probate venue in the Circuit Court of the county of residence (102 counties).
Federal: unified estate and gift schedule topping at 40%; basic exclusion $13,610,000 (2024), $13,990,000 (2025), $15,000,000 (2026); federal portability (DSUE) allowed; unlimited marital and charitable deductions; GST 40%.
Sets the federal exclusion and annual gift exclusion. Illinois exemption is static at $4,000,000.
Circuit Court probate venue; the estate tax is state-wide.Required. Please choose an Illinois county.
Select a county to see the Circuit Court venue, the small-estate affidavit threshold, and the federal and Illinois exclusions for the selected year.

Assets at date of death

Home, land, rental buildings at fair market value.Enter 0 or a positive amount.
Checking, savings, CDs, stocks, bonds, mutual funds.Enter 0 or a positive amount.
IRAs, 401(k)s, 403(b)s, pensions, annuity contracts.Enter 0 or a positive amount.
Death benefit includible when the decedent held any incident of ownership.Enter 0 or a positive amount.
Closely held business, vehicles, equipment, receivables, trusts includible in the estate.Enter 0 or a positive amount.
Illinois is a common-law (equitable distribution) state, not community property, so no community-property halving or double step-up applies.

Debts and administration costs

Deductible obligations of the decedent.Enter 0 or a positive amount.
Deductible when paid by the estate.Enter 0 or a positive amount.
Deductible administration expense.Enter a percentage between 0 and 25.
Filing fees, publication, appraisal costs.Enter 0 or a positive amount.
Deductible if not compensated by insurance.Enter 0 or a positive amount.

Bequests and marital status

Unlimited marital deduction for a citizen spouse or a QDOT (federal and Illinois).Enter 0 or a positive amount.
Unlimited deduction for qualifying charities.Enter 0 or a positive amount.

Prior gifts, portability and GST

Post-1976 taxable gifts; they count toward the federal exclusion and the Illinois $4,000,000 cliff test.Enter 0 or a positive amount.
Federal portability only; Illinois does not port its own exclusion.Enter 0 or a positive amount.
Federal GST at a flat 40% on Form 706 Schedule R.Enter 0 or a positive amount.
Equals the federal basic exclusion for the year of death.Enter 0 or a positive amount.

Gifting plan

Required in gifting mode. Annual-exclusion gifts are not taxable gifts.Required in gifting mode. Enter 1 or more donees.
Amounts above the annual exclusion become taxable gifts.Enter 0 or a positive amount.
Gifts carry over basis and lose the step-up at death.Enter 0 or a positive amount.
Illinois’s low $4,000,000 cliff can require many years; raise this if needed.Enter a whole number between 1 and 200.

How it works

  • Illinois has its own estate tax with a cliff. Estates at or below $4,000,000 (taxable estate plus adjusted taxable gifts) owe $0 to Illinois; once above, the ENTIRE Illinois taxable estate is taxed at graduated rates from 0.8% to 16% with no deduction for the exemption (Form IL-706). Rate schedule flagged VERIFY.
  • Federal estate tax also applies above the federal basic exclusion using the unified 18% to 40% schedule; the federal GST applies at 40% to direct skips above the allocated GST exemption.
  • Portability is federal only. A surviving spouse may inherit the unused federal exclusion (DSUE) with a timely Form 706; Illinois does not port its own exclusion.
  • No community property. Illinois is a common-law state, so no halving of community assets and no double basis step-up.
  • Elective share. A surviving spouse may renounce and take 1/3 of the estate if the decedent left descendants, else 1/2 (755 ILCS 5/2-8; VERIFY), modeled on the net estate.
  • Small estates. Small-estate affidavit where personal property is $100,000 or less (755 ILCS 5/25-1; VERIFY current figure).
  • Binding factor names what controls the result: the Illinois cliff, the federal exclusion, the federal unified schedule, or the GST.
  • Gifting mode uses the guarded bisection solver (60 expansions, 90 iterations, rounded up). Because the Illinois cliff is only $4,000,000, eliminating all tax usually requires many decades of annual-exclusion gifting — the calculator reports this honestly.
  • Gifting is not free. Carryover basis loses the step-up; the deferred gain is netted against the tax saved.

Sources

  • Illinois Estate Tax Act, 35 ILCS 405/, and Form IL-706 (state estate tax, decoupled, $4,000,000 exemption acting as a cliff, graduated rates 0.8% to 16%) — VERIFY current rate schedule with the Illinois Department of Revenue.
  • 755 ILCS 5/2-8 (spousal elective share 1/3 with descendants else 1/2; VERIFY); 755 ILCS 5/25-1 (small-estate affidavit, $100,000 personal property; VERIFY); Illinois probate venue in the Circuit Court of the county of residence (102 counties).
  • IRC chapter 11 unified schedule and exclusion ($13,610,000 / $13,990,000 / $15,000,000 for 2024 / 2025 / 2026); IRC 2010 portability; IRC 2042 life insurance inclusion; IRC 2055 charitable deduction; IRC chapter 13 GST at 40%; IRC 1014 step-up and 1015 carryover basis.
  • IRS Form 706 and Form 4768 instructions (9-month deadline, 6-month filing extension).

Test cases

TC1 – Below IL and federal exemptions. Cook, 2025, single. Real 2,000,000; financial 1,000,000; retirement 800,000; debts 200,000; funeral 15,000; atty 2%; court 400.
Gross 3,800,000; admin 72,400; deductions 287,400; net estate 3,512,600; TE 3,512,600 at or below 4,000,000 IL and 13,990,000 federal. Federal $0, Illinois $0, TOTAL $0. IL headroom 487,400; federal headroom 10,477,400.
TC2 – Above IL cliff, below federal. Cook, 2025, single. Real 4,000,000; financial 2,000,000; retirement 1,500,000; debts 300,000; funeral 20,000; atty 2%; court 400.
Gross 7,500,000; admin 144,400; deductions 464,400; net estate 7,035,600; TE 7,035,600 above 4,000,000. Illinois ~646,637 (entire TE taxed at graduated 0.8-16%). Federal $0. TOTAL ~646,637. Effective ~8.62%.
TC3 – Above IL cliff, marital + DSUE below federal. Cook, 2025, married 20 years, citizen spouse, descendants, bequest 5,000,000, DSUE 2,000,000. Real 12,000,000; financial 6,000,000; life 3,000,000; debts 400,000; funeral 25,000; atty 2%; court 400.
Gross 21,000,000; admin 412,400; deductions 837,400; net estate 20,162,600; less marital 5,000,000 = TE 15,162,600. Illinois ~1,868,096. Federal exclusion 15,990,000 so Federal $0. TOTAL ~1,868,096. Effective ~8.90%. Elective share 1/3 = 6,720,867.
TC4 – Gifting solver, 2026, maxYears 150. DuPage, single. Real 6,000,000; financial 4,000,000; retirement 2,000,000; business 1,000,000; debts 300,000; funeral 15,000; atty 2%; court 400; 4 donees at 19,000.
Gross 13,000,000; admin 254,400; deductions 629,400; net estate 12,370,600; TE 12,370,600. Illinois ~1,421,376; Federal $0 (below 15,000,000). Solver must reach the $4,000,000 IL cliff: 76,000/yr requires 111 YEARS (removes 8,370,600) – demonstrates the IL cliff makes annual-exclusion gifting impractical.
TC5 – Small estate, affidavit eligible. Sangamon, 2025, married 5 years, citizen spouse, descendants. Financial 60,000; retirement 20,000; debts 3,000; funeral 4,000; atty 2%; court 300.
Gross 80,000; admin 1,840; deductions 8,840; net estate 71,160; TE 71,160 at or below 4,000,000. Federal $0, Illinois $0, TOTAL $0. Affidavit available (personal property 80,000 at or below 100,000). Elective share 1/3 = 23,720.

Estimates only. Not legal, tax or financial advice. Illinois rate schedule and elective share are flagged for verification against 35 ILCS 405/ and 755 ILCS 5/2-8. Verify all figures with the Illinois Department of Revenue and federal rules before relying on them.

What Is an Illinois Estate Tax Calculator?

An Illinois Estate Tax Calculator estimates transfer taxes from estate assets, deductible costs, bequests, prior taxable gifts, portability, and certain generation-skipping transfers. This calculator applies its Illinois $4,000,000 cliff test, a graduated Illinois rate schedule, and the federal unified estate tax schedule for the selected year of death.

The calculator answers a practical question: how much federal and Illinois transfer tax does this estate produce under the values entered? It first builds the net estate, subtracts allowed marital and charitable deductions, applies any modeled annual-exclusion gifting, then calculates Illinois estate tax, federal estate tax, and federal GST tax before adding them together.

It has three modes. Estate mode estimates tax on the entered estate. Headroom mode shows whether tax applies and remaining federal exclusion. Gifting mode estimates how many years of annual-exclusion gifts are needed to reduce calculated transfer tax to zero, subject to the maximum years entered.

How the Illinois Estate Tax Calculator Formula Works

The calculation starts by adding five asset categories: real property, financial accounts, retirement accounts and annuities, includible life insurance, and business or other property.

Gross Estate=R+F+Ret+L+B\text{Gross Estate}=R+F+Ret+L+B

Here, R is real property, F is financial accounts, Ret is retirement accounts and annuities, L is includible life insurance, and B is business or other property. Administration cost equals the attorney and executor fee percentage applied to gross estate minus debts, never below zero, plus entered court costs.

The calculator then subtracts debts, funeral costs, administration costs, and casualty losses to find the net estate. In the formula, D is debts, Fun is funeral expense, Admin is administration cost, and Loss is casualty or theft loss. If the result would be negative, the code uses zero instead.

Net Estate=max⁡(0,Gross Estate−D−Fun−Admin−Loss)\text{Net Estate}=\max(0,\text{Gross Estate}-D-Fun-Admin-Loss)

If the decedent was married, the marital deduction is allowed only when the spouse is marked as a U.S. citizen or the bequest passes to a QDOT. The charitable deduction is limited to the amount remaining after the marital deduction. In the formula, TE is taxable estate, M is the allowed marital deduction, C is the charitable deduction, and GiftReduction is the modeled annual-exclusion gifting amount.

TE=max⁡(0,Net Estate−M−C−GiftReduction)TE=\max(0,\text{Net Estate}-M-C-GiftReduction)

For Illinois, the trigger is taxable estate plus earlier taxable gifts. If that total is at or below $4,000,000, Illinois tax is $0. If it exceeds $4,000,000, the code applies its graduated 0.8% to 16% schedule to the entire taxable estate. Federal tax is the federal progressive tax on taxable estate plus prior gifts minus the progressive tax on the federal exclusion plus DSUE. GST tax is 40% of direct skips above the entered GST exemption. In the total formula, T Federal and T Illinois are those two estate-tax amounts.

Total Transfer Tax=TFederal+TIllinois+0.40×max⁡(0,Direct Skips−GST Exemption)\text{Total Transfer Tax}=T_{Federal}+T_{Illinois}+0.40\times\max(0,\text{Direct Skips}-\text{GST Exemption})

For example, enter a 2025 estate with $7,500,000 of assets, $300,000 of debts, $20,000 of funeral costs, a 2% attorney fee, and $400 of court costs. Administration costs are $144,400. Net and taxable estate become $7,035,600. The code calculates Illinois estate tax of $646,636.80, displayed as $646,637, while federal estate tax is $0.

How to Use the Illinois Estate Tax Calculator: Step by Step

  1. Choose a mode: estate tax, larger-estate headroom, or gifting years needed to eliminate the calculated tax.
  2. Select the year of death. The code supports 2024, 2025, and 2026, which changes the federal exclusion and annual gift exclusion.
  3. Select the Illinois county of residence. The county changes the displayed Circuit Court venue, not the tax rate.
  4. Enter assets for real property, financial accounts, retirement accounts and annuities, includible life insurance, and business or other property.
  5. Enter debts, funeral expenses, the attorney and executor fee percentage, court costs, and casualty or theft losses.
  6. Set marital and descendant options, then enter any spouse bequest and charitable bequest. For a non-citizen spouse, select QDOT only when applicable.
  7. Enter earlier taxable gifts, DSUE, direct skips, and GST exemption allocated. The GST exemption field is not filled automatically by the year selector.
  8. For gifting mode, enter donees, gift per donee, unrealized gain, heirs’ capital-gains rate, NIIT choice, and maximum years to test.
  9. Check the acknowledgment box and calculate. Currency results are displayed in whole dollars, while effective tax rate is shown to two decimal places.

The main result is total transfer tax or, in gifting mode, the number of modeled gifting years. Supporting results show federal and Illinois tax, taxable estate, headroom, effective rate, filing indicators, probate venue, elective share, small-estate status, and three-year gifting projections.

What to Check Before You Rely on the Result

This calculator contains several useful planning assumptions, but its output is still an estimate. The code itself flags the Illinois rate schedule and elective-share rule for verification. It also uses fixed federal exclusions for 2024 through 2026 and a fixed $4,000,000 Illinois cliff. Results may differ from an actual estate tax return because valuation, deductions, filing rules, elections, tax law, and professional treatment can change the final liability.

Year of deathFederal basic exclusion in codeAnnual gift exclusion used in gifting mode
2024$13,610,000$18,000 per donee
2025$13,990,000$19,000 per donee
2026$15,000,000$19,000 per donee

The Illinois cliff can dominate the result

The code tests Illinois tax using taxable estate plus prior taxable gifts. At $4,000,000 or less, Illinois estate tax is zero. Above that point, the progressive Illinois schedule is applied to the full taxable estate rather than only the amount over $4,000,000. That makes the threshold especially important in the calculator’s output.

Gifting mode uses only the annual-exclusion amount

The modeled gift reduction per donee is the smaller of the entered gift and the annual exclusion for that year. Any entered amount above that cap does not increase the annual estate reduction in the solver. Earlier taxable gifts are handled separately through the prior-gifts field. A zero donee value is technically accepted by the current validation, but it produces no annual gifting reduction.

Some displayed planning lines have code-level limits

The current calculation object does not populate values used by the displayed “Net to other heirs,” “Deferred capital gains from carryover basis,” and “Net benefit” lines. Because the formatter converts missing numeric values to zero, those lines may display $0 even when other entered values suggest otherwise. Use the tax calculations and clearly populated fields separately from those affected outputs.

The small-estate indicator checks only financial accounts, retirement assets, life insurance, and business or other personal property against $100,000. Real property is not included in that test. The elective-share estimate uses one-third of net estate when descendants are selected and one-half when they are not. These are calculator rules, not legal, tax, or financial advice.

Estate Tax Calculators for All 50 U.S. States

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Frequently Asked Questions

How does the $4 million Illinois estate tax cliff work in this calculator?

The calculator adds taxable estate and earlier taxable gifts for the Illinois cliff test. If that amount is $4,000,000 or less, Illinois estate tax is $0. If it is higher, the code applies its graduated Illinois rate schedule to the entire taxable estate, not just the amount above $4,000,000.

Does this Illinois estate tax calculator include federal estate tax?

Yes. The calculator uses a federal progressive schedule with rates from 18% to 40%. It compares taxable estate plus prior taxable gifts with the selected year’s federal basic exclusion plus any entered DSUE. Federal estate tax is the schedule tax on the federal base minus the schedule tax on the applicable exclusion.

Does Illinois inheritance tax appear in the calculation?

The code sets Illinois inheritance tax to $0 in every calculation. Total transfer tax can still include Illinois estate tax, federal estate tax, and federal GST tax. The result section displays Illinois inheritance tax separately, but it does not add any Illinois inheritance-tax amount to the total.

How does the calculator handle a surviving spouse?

A spouse bequest receives the calculator’s marital deduction only if the married box is selected and the spouse is marked as a U.S. citizen or the QDOT box is selected. The deduction cannot exceed the net estate. The calculator also estimates an elective share from the net estate using the descendant selection.

How does gifting mode calculate the number of years?

Gifting mode multiplies the allowed annual gift per donee by the number of donees and modeled years, then reduces taxable estate by that amount. A bisection solver searches up to the maximum years entered for the first whole year that brings total calculated transfer tax to zero. If it cannot, the tool reports more than the limit.

How accurate is this Illinois estate tax calculator?

It is an estimate that follows the formulas and fixed values coded into the tool. The code itself marks the Illinois rate schedule, elective-share rule, and small-estate figure for verification. Actual estate tax can change with valuations, elections, deductions, filing positions, tax law, and facts that this calculator does not model.

What counts as a small estate in this calculator?

The calculator marks a small estate when financial accounts, retirement accounts, includible life insurance, and business or other personal property total $100,000 or less. It does not include real property in that specific test. The code presents the result as possible small-estate affidavit availability and flags the current threshold for verification.

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