Illinois Estate Tax Planning
Last updated: 18 Oct 2025 • Author: Alexander Foelsche CPA (US), WP (DE), RE (CH)
Illinois Estate Tax — Planning Guide
Practical strategies to reduce, defer, and fund Illinois estate tax under 35 ILCS 405. Coordinate state and federal rules, leverage the separate Illinois-only QTIP election, manage nonresident situs exposure, support valuations, and plan liquidity for the 9-month payment.
Top planning moves (at a glance)
Design bequests & trusts
- IL-only QTIP: Make a marital deduction election on the Illinois return even if no federal QTIP is made. Preserve control over remainder while deferring IL tax.
- Credit shelter trust: Use federal exclusion efficiently; coordinate with Illinois computation to capture state benefits where possible.
- Charitable design: Outright bequests or CRT/CLT to reduce the Illinois base and align income-tax goals.
- Disclaimer planning: Allow post-mortem pivots to optimize IL vs. federal outcomes.
Manage situs & beneficiaries
- Nonresidents: Limit IL-situs assets; avoid creating business situs for intangibles through Illinois-centered management.
- Beneficiary mix: Direct high-tax assets toward charitable/spousal vehicles; use bequest clauses to allocate tax efficiently.
- Entity planning: Keep entity records/management outside IL to reduce situs risk for otherwise intangible interests.
Common structures
| Tool | Primary goal | Practice notes |
|---|---|---|
| Illinois-only QTIP trust | Defer Illinois tax at first death | Elect on a timely filed Form 700; include detailed asset schedules and an election statement. Track for inclusion at survivor’s death (IRC §2044 concept for IL). |
| Credit shelter / bypass trust | Use federal exclusion; shelter appreciation | Coordinate the interrelated IL computation; ensure asset tracing and basis records are maintained. |
| Charitable bequests / CRT / CLT | Reduce Illinois taxable base | Verify qualified status; attach governing instruments and valuation support. |
| Lifetime gifts | Shift growth out of the estate | Model federal gift/GST consequences; maintain documentation and avoid IL business-situs footprints for intangibles. |
| IL real estate holding strategy | Manage nonresident exposure | Consider pre-death sales/exchanges or aligning ownership with beneficiaries who yield better after-tax outcomes. |
| §6166 installment plan | Liquidity for closely held business interests | If federal §6166 applies, Illinois generally aligns proportionally for Illinois-situs business property; keep elections and schedules consistent. |
Valuation, deductions & documentation
Valuation playbook
- Engage qualified local appraisers for Illinois real property and significant tangibles.
- Keep federal and Illinois schedules synchronized; reconcile any alternate valuation decisions.
- Document discounts for closely held interests with robust reports.
Deductions & proof
- Obtain probate/court approvals where required for administration expenses.
- Retain invoices, engagement letters, and proof of payment; follow the AG attachment checklist.
- For nonresidents, tie deductions to Illinois-situs property where necessary.
Liquidity & timing
Cash at 9 months
- Illinois return Form 700 is due at 9 months; payment is also due at 9 months.
- Use ILIT proceeds or staged asset sales to prevent interest/penalties.
Installments & remittance
- Model §6166 if closely held business interests are present; align Illinois schedules with the federal election.
- Remember: file with the Attorney General, but remit tax to the Illinois State Treasurer; keep proof of payment.
Suggested planning workflow
- Inventory & map Illinois-situs vs. non-Illinois assets; identify beneficiaries and goals.
- Model scenarios with the IL calculator; test IL-only QTIP, charitable, and gifting options.
- Draft documents (wills, trusts, beneficiary designations, disclaimer language) reflecting IL computation and liquidity objectives.
- Assemble proof (appraisals, court approvals, invoices) for deductions and elections; prepare QTIP schedules if applicable.
- Execution & review: retitle assets, update designations, and set review triggers for life events and law changes.
FAQs
Does Illinois have portability?
No. Illinois does not offer portability of a deceased spouse’s unused exclusion. Consider an Illinois-only QTIP or credit shelter trust to manage exposure.
Can I make a state QTIP without a federal QTIP?
Yes. Illinois permits a separate state QTIP election on a timely filed Form 700. Maintain detailed schedules and an election statement.
What’s the simplest way to lower Illinois exposure?
Combine charitable and marital/QTIP planning, document deductions thoroughly, and manage situs for nonresidents. Maintain liquidity to meet the 9-month payment.
How do I handle a pending sale of Illinois property?
Coordinate appraisals and closing dates so funds are available for the Illinois payment; ensure the sale documentation matches reported values.