You believe your insurer handled your claim in bad faith. The harder question is what it takes to prove it. Illinois law routes bad faith through a specific, demanding standard, and the proof you can assemble before filing suit often decides whether a Section 155 claim clears that bar.
This guide focuses on the proof side — what the law requires you to establish, what evidence actually moves the needle, and how to preserve it while the trail is still warm. For the full legal framework on Section 155, penalties, and deadlines, see Mag Mile Law’s guide to bad faith insurance claims in Illinois.
What You Have to Prove
Illinois does not have a standalone bad faith tort for first-party claims. Your claim runs through 215 ILCS 5/155, which attaches to a breach-of-contract claim and lets a court award attorney fees, costs, and a capped penalty where the insurer’s conduct was “vexatious and unreasonable.” Cramer v. Insurance Exch. Agency, 174 Ill. 2d 513 (Ill. 1996). The burden is not that the insurer was wrong — it is that the insurer had no bona fide basis for its position or handled the claim in a way that falls outside reasonable claim handling. Courts assess the full picture under a totality-of-the-circumstances approach. For the full legal framework, see our guide on [bad faith insurance claims in Illinois].
Practically, this means your proof has to show two things: that the insurer owed you under the policy, and that the path it took to deny, delay, or underpay was unreasonable on its face.
What Evidence Actually Matters
The insurer’s claim file
The single most valuable piece of evidence in a Section 155 case is usually the insurer’s own claim file. Adjuster notes, internal estimates, supervisor reviews, coverage counsel memoranda, and photos of the loss all live there. So do the time stamps that show how long each step of the review actually took.
You cannot get the claim file informally — the insurer will not volunteer it. You obtain it through discovery once suit is filed. But what you can do before suit is preserve your right to it: do not sign a release, do not agree to limit discovery, and document every date on which you gave the insurer information so that any later claim that “we were still waiting on documents” can be tested against the record.
The denial letter, read against the regulation
Under 50 Ill. Admin. Code § 919.50(a)(1), a written denial must clearly set forth the policy definition, limitation, exclusion, or condition on which the denial is based. That is not a formality. A denial letter that cites a generic exclusion without tying it to the facts — or that shifts grounds from what the adjuster said on the phone — is itself evidence. Read your denial letter sentence by sentence against the regulation. Note what it cites and what it does not. Note whether it matches the adjuster’s prior communications. Preserve every prior version.
Your own records
Contemporaneous records made during the claim are persuasive in a way that later reconstruction is not. Keep:
- Every letter, email, voicemail, and text the insurer sent
- A phone log with date, time, adjuster name, and a short note of what was said
- Every document, photograph, estimate, and receipt you sent the insurer — and the method of delivery
- Your own repair estimates and contractor bids, with dates
- Any public-adjuster or independent-engineer reports you commissioned
If you kept nothing contemporaneous, reconstruct now. Get sworn declarations from your contractor, your public adjuster, or family members who overheard calls. Pull phone records to establish call dates. Print emails to PDF so metadata is preserved.
Pattern evidence
No single factor controls a totality-of-the-circumstances analysis, but certain patterns carry weight. Look for:
- Silence gaps. Long stretches with no insurer communication, particularly after you sent information.
- Desk-only reviews where the policy or the loss required an onsite inspection — the adjuster never visits, never scopes, and issues a conclusion based on photos.
- Rejection of your expert’s work without the insurer commissioning its own, or the insurer’s expert reaching a conclusion materially disconnected from the physical evidence.
- Shifting grounds — the denial is based on reason A, then after you rebut it, reason B appears. Coverage positions that migrate during handling are often reconstructions.
- Holdback of the undisputed amount. If the insurer concedes that part of your loss is covered but does not tender payment on that part, that conduct alone can support a Section 155 finding. Millers Mut. Ins. Ass’n v. House, 286 Ill. App. 3d 378 (5th Dist. 1997).
The bona fide dispute counter-narrative
Expect the insurer to argue that it had a genuine, fact-based disagreement about coverage — the “bona fide dispute” defense. The defense is not self-proving. An assertion of a coverage defense without a factual basis does not create a bona fide dispute. McGee, 315 Ill. App. 3d at 683. Your proof needs to anticipate this: what is the insurer likely to say was reasonable about its position, and what specific facts from the claim file contradict it?
How Regulatory Violations Become Proof
Illinois regulates insurer claim handling through 215 ILCS 5/154.6 and 50 Ill. Admin. Code Part 919. Those rules do not give you a private cause of action — Purlee v. Liberty Mut. Fire Ins. Co., 260 Ill. App. 3d 11 (5th Dist. 1994) — but violations become evidence in a Section 155 case.
The practical move is to line up every regulatory deadline against the dated facts from your own records. A response owed in 15 working days that arrived on day 40. An investigation that should have started within 21 working days but produced no contact for two months. A denial that did not specify the policy language it relied on, as § 919.50(a)(1) requires. Each miss, backed by dates and documents, is a fact the court weighs in the totality analysis.
Preserving Evidence Before You File
The moment you suspect bad faith, the evidence window starts to narrow. Three preservation moves matter most:
- Send a written loss narrative and request the complete policy. This forces the insurer to respond in writing and creates a dated record of what you told them and when.
- Do not give a recorded statement without counsel. Recorded statements get selectively deployed against insureds later. If the insurer requests one, you can comply in writing instead.
- File a sworn proof of loss promptly, even if the policy has not formally required it yet. Under 215 ILCS 5/143.1, filing a proper proof of loss tolls the policy’s suit-filing deadline until the insurer denies the claim in whole or in part. It also locks in your position.
Also consider filing a complaint with the Illinois Department of Insurance in parallel. A DOI complaint creates an independent, dated regulatory record that can corroborate your version of the chronology later. For more on the DOI process and how it interacts with a court case, see the bad faith insurance hub.
If You Prove It
Proof supports recovery on two tracks. First, the underlying breach of contract — the policy benefits your insurer should have paid. Second, Section 155 relief on top: attorney fees, costs, and a capped statutory penalty. Illinois also allows consequential damages and prejudgment interest in appropriate cases. For the full damages breakdown, see our guide on [bad faith insurance claims in Illinois].
Watch Your Deadlines
Two clocks apply. Your breach-of-contract claim must meet the policy’s suit-filing deadline — often one to two years from the date of loss in property policies. The Section 155 claim is subject to the five-year catch-all statute of limitations under 735 ILCS 5/13-205. Marcheschi v. Illinois Farmers Ins. Co., 298 Ill. App. 3d 306 (1st Dist. 1998). A timely, sworn proof of loss tolls the policy clock under 215 ILCS 5/143.1. For tolling, estoppel, and the full deadline analysis, see the bad faith insurance hub.
Frequently Asked Questions
Can I collect proof on my own before hiring a lawyer?
Yes — and the proof you collect before counsel is often the most valuable. Most of what matters is preservation: keep every communication, log every call, photograph every piece of physical damage, and save every estimate. What requires counsel is the discovery of the insurer’s internal file and the framing of the evidence against the vexatious-and-unreasonable standard.
How much of the insurer’s own file will I actually see?
Through discovery in a filed lawsuit, typically the adjuster notes, internal estimates, photos of the loss, supervisor communications, and non-privileged portions of any coverage-counsel review. The insurer will claim work-product and attorney-client privilege over some material. Fights over the scope of claim-file production are common and are often where bad faith cases are won or lost.
Is circumstantial evidence enough?
Usually, yes. Bad faith cases rarely involve a smoking-gun email. Totality analysis runs on patterns — dates that do not line up, positions that shift, investigations that did not happen. Dates and documents accumulated from your own records and the insurer’s file are the backbone of most Section 155 findings.
Proving Bad Faith Starts With the File You Build Now
If your insurer denied or delayed your claim without a legitimate basis, the record you build in the weeks and months before suit often determines how a court sees it later. Every dated communication, every preserved document, every instance where the insurer missed a regulatory deadline becomes part of the totality a Section 155 court reviews.
Mag Mile Law handles first-party property insurance coverage disputes in Cook, DuPage, Lake, Will, and Kane counties and the Northern District of Illinois. Attorney Steven Mikuzis, a cum laude graduate of Chicago-Kent College of Law and winner of the CALI Award for Trial Advocacy, and Attorney Mario Iveljic, who earned his J.D. cum laude from Chicago-Kent and his B.A. in Economics from Yale, bring over 20 years of combined insurance coverage litigation work. To discuss your options after a denied or delayed claim, contact Mag Mile Law at (773) 644-9593.
This article is for general informational purposes only and does not constitute legal advice. Prior results do not guarantee a similar outcome. Reading this article or contacting Mag Mile Law does not create an attorney-client relationship.