Illinois estate tax chart
Date: 2026-07-13
Educational only — not legal or tax advice. Compare to IL AG calculator and illinois-estate-tax-computation.
Assumptions
| Input | Value |
|---|---|
| Calculator | ~/.cursor/skills/illinois-estate-tax/scripts/il_estate_tax.py |
| Mode | current_law (35 ILCS 405; IRC §2011 as of 12/31/2001 + $4M IL exclusion) |
| Form 700 line 1 | Tentative taxable estate (varies below) |
| QTIP (line 2) | $0 |
| Adjusted taxable gifts (line 4) | $0 |
| Illinois situs | 100% (default; lines 7–9 not overridden) |
| Death date | 2026-01-01 (2013+ law metadata) |
Estate sizes: $3,800,000 through $10,000,000, step $400,000 (17 points; $10,000,000 included as endpoint).
Data
| Estate (line 1) | IL estate tax |
|---|---|
| $3,800,000 | $0 |
| $4,200,000 | $57,143 |
| $4,600,000 | $171,428 |
| $5,000,000 | $285,714 |
| $5,400,000 | $392,446 |
| $5,800,000 | $434,643 |
| $6,200,000 | $477,500 |
| $6,600,000 | $520,357 |
| $7,000,000 | $565,603 |
| $7,400,000 | $610,993 |
| $7,800,000 | $656,690 |
| $8,200,000 | $704,577 |
| $8,600,000 | $752,465 |
| $9,000,000 | $801,049 |
| $9,400,000 | $851,399 |
| $9,800,000 | $901,748 |
| $10,000,000 | $926,923 |
Chart
Tentative taxable estate on x-axis ($1,000,000); Illinois estate tax on y-axis ($1,000s).
xychart-beta
title "Illinois estate tax vs tentative taxable estate (100% IL situs, current law)"
x-axis "Estate value ($1,000,000)" ["3.8", "4.2", "4.6", "5.0", "5.4", "5.8", "6.2", "6.6", "7.0", "7.4", "7.8", "8.2", "8.6", "9.0", "9.4", "9.8", "10.0"]
y-axis "IL tax ($1,000s)" 0 --> 1000
line [0, 57, 171, 286, 392, 435, 478, 520, 566, 611, 657, 705, 752, 801, 851, 902, 927]
%% Full series (estate → tax): 3800000→0, 4200000→57143, 4600000→171428, 5000000→285714, 5400000→392446, 5800000→434643, 6200000→477500, 6600000→520357, 7000000→565603, 7400000→610993, 7800000→656690, 8200000→704577, 8600000→752465, 9000000→801049, 9400000→851399, 9800000→901748, 10000000→926923
Interpretation
- No tax below $4M: At $3.8M tentative taxable estate, Illinois tax is $0 — consistent with the $4,000,000 Illinois exclusion under current law.
- Tax begins above $4M: From $4.2M, tax is ~$57k and rises in roughly ~$114k per $400k of estate through $5.0M (~6.9% of the increment in that band), reflecting the legacy state death tax credit table plus interrelated iteration while the federal 40% cap binds.
- Kink near $5.4M: Growth slows after $5.0M ($5.0M→$5.4M adds ~$107k, not
$114k); from $5.4M onward the marginal step is **$40–50k per $400k** (~1% effective on increments) when the federal cap no longer applies. - Upper range: Tax continues to climb roughly linearly at that slower marginal rate; $10M endpoint is $926,923 (~9.3% of $10M tentative estate in this scenario).
Related: hb2368 (proposed flat-rate reform, not enacted).