How to File Illinois Form 700 Without a CPA — What's Possible and What's Not

An executor can file Illinois Form 700 — the Illinois Estate and Generation-Skipping Transfer Tax Return — without hiring a CPA. The Attorney General's office accepts pro se filings and there is no legal requirement that Form 700 be prepared by a licensed professional. Whether self-filing is practical for your estate depends on a clear-eyed assessment of its complexity: specifically, whether the interrelated calculation is straightforward, whether the asset inventory is complete, and whether any business valuations, prior-year gifts, or non-resident complications are involved.

This page walks through what self-filing requires, what the real risks are, and where the line is between a manageable DIY filing and one that needs professional preparation.

What Self-Filing Form 700 Actually Requires

Form 700 is the Illinois Estate and Generation-Skipping Transfer Tax Return. It is filed with the Illinois Attorney General's Revenue Litigation Bureau — not IDOR. This distinction trips up many executors who assume estate-related state filings go to the state revenue department. The wrong mailing address means a missed deadline and compounding interest.

Office locations:

• Cook, DuPage, Lake, and McHenry counties: Chicago office
• All other Illinois counties: Springfield office

To file Form 700 without a CPA, you need to gather and prepare the following:

Required attachments:

• Complete copy of the federal estate tax return (Form 706) if one was required. If no Form 706 is required (estates under the federal $15 million threshold), the Illinois return must still include a computation of the federal taxable estate using Form 706 format
• Schedule A: Inventory of assets with date-of-death values for all categories (real estate, stocks, bonds, mortgages, cash, business interests, other miscellaneous property, transfers, powers of appointment, insurance)
• Appraisals for real estate and any closely held business interests
• A copy of the will or trust document
• Any documentation supporting claimed deductions (debt statements, funeral invoices, executor fee estimates)

The interrelated calculation: This is the most technically demanding part of a self-prepared Form 700. Illinois computes the estate tax using the pre-2001 federal estate tax credit tables. The "interrelated" aspect refers to the fact that the Illinois estate tax itself is deductible on the federal return (if applicable), which changes the federal taxable estate, which changes the credit, which changes the Illinois tax — a circular calculation. For estates near the $4 million threshold, this calculation requires careful iteration.

For estates well above $4 million, the math becomes more consequential. For estates just over $4 million, a single iteration typically produces an acceptably accurate result. The guide includes a worked example.

Payment procedure: Payment is not made to the AG. Tax owed goes to the Illinois State Treasurer — by check, ACH, or ePAY, with the specific Estate Tax Payment Form. Filing the return with the AG and sending payment to the Treasurer as a separate action is not obvious and is one of the most common procedural errors in self-filed returns.

Step-by-Step: The Self-Filing Process

Step 1: Determine whether Form 700 is required If the gross estate — including retirement accounts, life insurance where the decedent owned the policy, jointly held property, and probate assets — exceeds $4,000,000, Form 700 is required. If it does not, you do not need to file (though some executors file to clear the state's automatic lien on real property even when no tax is owed).

Use the Gross Estate Calculation Worksheet to run this calculation before anything else. Getting this determination right determines everything that follows.

Step 2: Apply for the estate EIN The estate needs a Federal Employer Identification Number (EIN) as a separate taxable entity from the decedent. Apply online through the IRS at irs.gov. The EIN is required for all tax filings and to open the estate's bank account.

Step 3: Compile the Schedule A inventory Every asset in the gross estate needs a date-of-death value. Real estate requires a licensed Illinois appraiser's certificate. Securities use the average of the high and low quoted prices on the date of death (or the mean of the weekly high and low for assets without a daily market price). Retirement accounts use the account balance as of the date of death. Life insurance uses the face value of any policy where the decedent held incidents of ownership.

Step 4: Complete the federal tax computation Even if no Form 706 is required (because the federal threshold is not crossed), Form 700 uses federal computation as its starting point. You will need to prepare at minimum the Schedule A–M equivalent of Form 706 to establish the adjusted taxable estate figure. This is the base on which the Illinois calculation runs.

Step 5: Run the interrelated calculation Illinois Regulation 86 Ill. Adm. Code Part 2000 provides the calculation method. The state estate tax is calculated by reference to the maximum state death tax credit from pre-2001 federal tables. The interrelated element requires either iterative calculation or the formula provided in the form instructions.

Step 6: Prepare and mail Form 700 Mail to the correct AG office — Chicago or Springfield depending on the county of the decedent's last domicile. Include all required attachments. Keep a copy of everything you send, ideally mailed with tracking confirmation.

Step 7: Send payment to the State Treasurer Prepare the Estate Tax Payment Form and send payment to the Illinois State Treasurer. Do not mail payment to the AG. Keep the payment confirmation.

Step 8: Receive Certificate of Discharge The AG's office reviews the return and issues a Certificate of Discharge once the estate tax liability is settled. This certificate releases the state's automatic lien on all real property in the estate. It must be recorded at the county Recorder of Deeds for each county where the estate holds real property.

When Self-Filing Is Realistic

Self-filing Form 700 is most realistic when:

• The estate consists primarily of financial accounts, publicly traded securities, and a primary residence with a straightforward appraisal
• The estate clearly exceeds $4 million (the threshold determination is not in doubt)
• There are no prior-year taxable gifts that would affect the Form 700 base
• There are no business interests requiring professional valuation
• There is no non-resident issue (decedent was domiciled in Illinois, all assets are Illinois-sited or clearly categorized)
• The executor is comfortable with multi-step financial calculations and organized document management

The guide provides all the conceptual grounding and procedural walkthrough needed for this type of estate.

When Self-Filing Creates Real Risk

Business interests: Closely held businesses, farms, and professional practices require a qualified professional appraisal. The AG's office audits these. An undervalued appraisal that artificially puts the estate below $4 million is an audit target. An executor who lacks the experience to evaluate an appraisal's adequacy should not be self-filing a return that includes one.

Prior-year taxable gifts: If the decedent made taxable gifts in prior years that exceeded the annual exclusion, those gifts are added back to the estate for Form 700 purposes. Tracking down prior-year gift tax returns (Form 709) and incorporating them correctly requires experience with the cumulative lifetime gift calculation.

Non-resident estate issues: If the decedent was domiciled outside Illinois but held Illinois real estate or other Illinois-sited assets at death, the apportionment calculation requires specific expertise.

Estates right at the threshold: An estate at $4.05 million — where the difference between filing and not filing is $100,000 in legitimate deductions — is not the right place to make calculation errors. The financial stakes of getting the threshold determination wrong are disproportionate.

QTIP elections or partial marital deduction: If the estate plan involves a qualified terminable interest property trust, the marital deduction claimed on Form 700 requires specific knowledge of the QTIP rules. An incorrect election cannot easily be undone.

The Guide's Role in Self-Filing

The Illinois Final Tax & Estate Tax Guide does not replace professional CPA or attorney representation when representation is warranted. What it provides:

• A complete walkthrough of Form 700, section by section, in plain language
• The Three-Agency Filing Roadmap identifying exactly which form goes to which agency with full mailing addresses
• The Gross Estate Calculation Worksheet for the threshold determination
• The interrelated calculation explained with a worked example
• The full Forms and Agency Reference sheet with every form name, agency, address, and phone number
• The complete deadline calendar so the nine-month deadline and extension procedures are tracked
• The CPA Preparation Packet if you ultimately decide professional help is appropriate

The guide was built specifically for Illinois executors who want to understand the process — whether they complete it themselves or hand off to a professional with full context.

The Income Tax Filings That Run Alongside Form 700

Filing Form 700 is one of three possible Illinois tax filings after a death. The others:

IL-1040 (final income tax): The decedent's last individual income tax return, filed with IDOR, covering January 1 through the date of death. Due April 15 of the following year, or October 15 with extension. An executor signs the return and claims the refund using Form IL-1310 with the court-issued Letters of Office attached.

IL-1041 (fiduciary income tax): If the estate generates income during administration — bank interest, dividends from securities held in the estate, rental income — that income is taxed at the estate level. The filing threshold follows federal rules (gross income of $600 or more during the tax year generally requires a federal Form 1041, and Illinois piggybacks on that threshold for IL-1041). Filed with IDOR.

These two filings go to IDOR. Form 700 goes to the AG. All three are separate deadlines and separate submissions.

Frequently Asked Questions

Can an executor file Form 700 themselves without being an attorney? Yes. There is no requirement that Form 700 be prepared by a licensed attorney or CPA. Executors file pro se returns routinely. The AG's office processes them the same as professionally prepared returns. The risk is entirely about return accuracy, not about whether the preparer holds a license.

What happens if I send Form 700 to IDOR instead of the AG? IDOR will not process it. Estate tax is not within IDOR's jurisdiction. IDOR may send it back or simply hold it. The nine-month deadline runs from the date of death regardless of where the form was sent, so an incorrectly addressed filing does not stop the clock. File with the correct AG office from the start.

What happens if I send the payment to the AG instead of the State Treasurer? The AG does not process payments. Payment sent to the AG instead of the State Treasurer will be returned or redirected, but during that time it is not credited against the estate's tax liability. Interest accrues. Send the payment with the Estate Tax Payment Form directly to the State Treasurer.

Is there a penalty for filing Form 700 late? Yes. Interest accrues on unpaid Illinois estate tax from the original nine-month due date at the statutory rate. Late filing penalties also apply. An extension of time to file does not extend the time to pay — interest accrues on any unpaid tax from the nine-month deadline even if the return is filed later under an extension.

What is the six-month extension and how do I apply? The Illinois estate tax extension is generally available on written application to the AG's office, typically in coordination with the federal extension (Form 4768 filed with the IRS). The extension extends the time to file the return, not the time to pay. If you request an extension but do not pay an estimate of the tax owed, interest will accrue on the unpaid amount from the original nine-month deadline.

Where is the complete guide for filing Illinois Form 700? The Illinois Final Tax & Estate Tax Guide provides a section-by-section Form 700 walkthrough, the interrelated calculation with worked examples, and the Three-Agency Filing Roadmap as a standalone printable tool.

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