Illinois Estate Tax Calculator

A.H.Steinmetz, Ltd. provides an Illinois estate tax calculator to help individuals estimate potential Illinois estate tax liability based on current state law. Illinois imposes an independent estate tax that operates separately from federal estate tax rules, and proper planning is often essential to avoid unnecessary tax exposure.

A.H.Steinmetz, Ltd. serves clients throughout Monroe, St. Clair, Madison, and surrounding counties in Illinois, as well as St. Louis, Jefferson, St. Charles, and surrounding counties in Missouri. Virtual appointments are available for clients who prefer remote consultation.

Illinois Estate Tax Calculator

Enter the approximate value of the gross estate and any prior taxable gifts. This tool provides an estimated Illinois estate tax calculation based on the modified IRC §2011(b) state death tax credit system used by the Illinois Attorney General. For exact results, confirm with Illinois Form 700 and the AG calculator.

Understanding the Illinois Estate Tax

Illinois imposes a state-level estate tax using a modified version of the federal State Death Tax Credit (IRC §2011(b), as it existed on December 31, 2001), combined with an Illinois-specific limitation under §2011(e). Through this credit-and-limitation structure, Illinois effectively provides a $4,000,000 exclusion equivalent—meaning that estates at or below this threshold owe no Illinois estate tax, even though Illinois does not have a statutory exemption or unified credit of its own.

Unlike federal law, Illinois does not allow portability of this exclusion. If the first spouse dies without proper planning—such as a Bypass Trust—their unused Illinois exclusion is lost permanently, which may result in substantial Illinois estate tax when the surviving spouse later passes.

Illinois calculates estate tax based on:

  • The Illinois Tentative Taxable Estate,
  • Adjusted Taxable Gifts made after 1976,
  • The mandatory $60,000 adjustment used in the federal credit system, and
  • A comparison of the tax under §2011(b) and the limitation under §2011(e).

Because the Illinois estate tax is deductible for its own computation, the calculation requires an iterative process.


Key Features of Illinois Estate Tax Law

1. $4,000,000 Illinois Exclusion Equivalent

Illinois does not subtract a statutory exemption. Instead, the exclusion arises through the credit-limitation formula.
If the combined Illinois Tentative Taxable Estate and Adjusted Taxable Gifts are at or below $4,000,000, no Illinois estate tax is due.

2. No Portability Between Spouses

Illinois does not permit a surviving spouse to use the deceased spouse’s unused exclusion. Bypass Trust planning is essential for married couples wishing to preserve both spouses’ Illinois exclusion equivalents.

3. Graduated Effective Rate Structure (0.8% to 16%)

Illinois does not apply a flat rate or marginal bracket system. Instead, the state applies the pre-2001 federal State Death Tax Credit table, which produces effective rates ranging from 0.8% to 16% depending on estate size.

4. The Illinois “Threshold Effect”

Illinois does not tax the entire estate once the threshold is exceeded.
Instead:

  • The first dollars above $4,000,000 face a sharp marginal increase in tax,
  • But the entire estate is not taxed at the highest rate.

For example, a $4.1 million estate, without lifetime gifts, will result in approximately $28,571 in Illinois estate tax.

This effect is created by the interaction of the §2011(b) credit table and the §2011(e) limitation that incorporates the Illinois exclusion equivalent.

5. Illinois Situs Property of Nonresidents May Be Taxable

Nonresidents who own Illinois real estate or Illinois-situs tangible property may still incur Illinois estate tax.
Apportionment rules apply.

Common Planning Strategies to Reduce Illinois Estate Tax

Illinois estate tax exposure can often be reduced or eliminated with a properly structured estate plan. Common strategies include:

  • Bypass (Credit Shelter) Trusts
    Preserve the first spouse’s Illinois exclusion equivalent rather than losing it at the first death.
  • Lifetime Gifting Strategies
    Utilize annual exclusion gifts, lifetime transfers, valuation-discounted gifts, and 529 contributions to reduce the taxable Illinois estate.
  • Irrevocable Trusts
    Use ILITs, GRATs, SLATs, CRATs, CRUTs, and Dynasty Trusts to remove appreciating assets from the taxable estate.
  • Business Succession Planning
    Use Family Limited Partnerships (FLPs) and Family Limited Liability Companies (FLLCs), and properly documented business valuations to reduce the taxable value of closely held business interests.

Our Approach to Illinois Estate Tax Planning

A.H.Steinmetz, Ltd. integrates Illinois estate tax analysis into every estate plan we prepare. Our services include:

  • Evaluating potential Illinois estate tax liability
  • Designing trust structures to preserve exclusion amounts
  • Implementing lifetime gifting strategies
  • Coordinating valuations and appraisals
  • Structuring multi-generational estate and asset-protection strategies
  • Assisting with Illinois estate tax filings during administration

Proper planning can significantly reduce—or completely eliminate—Illinois estate tax liability.

Schedule a Consultation

Contact us today or book an appointment to schedule a confidential consultation to discuss Illinois estate tax planning or to obtain a formal estate-tax analysis. Virtual and in-person appointments are available.