Illinois medical billing and payer rules

Timely filing in Illinois

Illinois surprise billing vs the federal NSA

Fully insured PPO, HMO and comprehensive voluntary plans regulated by Illinois follow Section 356z.3a negotiation and binding arbitration. Self-funded employer plans follow the federal No Surprises Act and federal IDR. We confirm the plan type before filing either dispute.

Major payers

How does Illinois Medicaid billing work?

Illinois Medicaid is run by the Illinois Department of Healthcare and Family Services (HFS). Fee-for-service claims go to HFS through its Medical Electronic Data Interchange system, called MEDI, and managed care claims go to the health plan the patient is enrolled in.

Every provider enrolls through the Illinois Medicaid Program Advanced Cloud Technology system, called IMPACT, and HFS tells providers to be enrolled there before they contract with any plan. A hospital that submits claims for employed physicians enrolls as the billing provider, and each physician enrolls as a rendering provider tied to it. The Chapter 100 provider handbook lists the prerequisites: an NPI, a taxonomy code, a certified W-9 on file with the State Comptroller where the provider is paid directly, and an active license at revalidation.

The most common Illinois Medicaid error is billing the wrong payer. HFS says to verify eligibility for the date of service, not today's date, in MEDI, the Recipient Eligibility Verification system or by phone at 800-842-1461. Our Medicaid payer guide covers the national rules.

What is the Illinois Medicaid timely filing limit?

Illinois Medicaid fee-for-service claims must reach HFS within 180 days of the date of service, or within 180 days of discharge for hospital inpatient claims. Topic 112.4 of the HFS Chapter 100 handbook applies the limit to initial and resubmitted claims, and says claims received after day 180 will not be paid.

Topic 112.4.1, last revised October 2023, lists exceptions. Most need an HFS 1624 override request for professional claims or an HFS 1624A for institutional claims.

Managed care is different. HFS's Managed Care Manual says plans may set different timely filing requirements than the Department in their provider subcontracts, so we load each plan's filing, corrected claim and appeal days from the signed contract.

Which managed care plans does HealthChoice Illinois use?

HFS runs three care coordination programs: HealthChoice Illinois (HCI), YouthCare and the Medicare-Medicaid Alignment Initiative (MMAI). HCI is the statewide program for most Medicaid customers, including families and children, adults covered under the Affordable Care Act, and seniors and adults with disabilities who are not eligible for Medicare.

HFS's provider relations contact list, revised January 2025, shows these HCI plans: Aetna Better Health, Blue Cross Community Health Plans, CountyCare Health Plan, Meridian and Molina Healthcare. The MMAI plans on it are Aetna, Blue Cross, Humana, Meridian and Molina. HFS publishes a managed care map by county, so check it before assuming a plan serves your area.

For plan enrollees, bill the health plan directly. Patients in the Primary Care Case Management program, Illinois Health Connect, are the exception and go to HFS fee-for-service. The Managed Care Manual says a plan must pay at least the Department's rate for appropriate emergency services from a non-affiliated provider, and must pay 90 percent of clean claims within 30 days and 99 percent within 90 days of receipt.

If a plan will not resolve a problem, HFS runs a Managed Care Provider Resolution Portal. The handbook says HFS replies within 2 business days to an urgent complaint and within 15 business days to anything else. Work the plan's own process first and keep the case numbers.

Who is the Medicare MAC for Illinois?

National Government Services, Inc. (NGS) is the A/B Medicare Administrative Contractor for Illinois, in Jurisdiction 6 (J6). The CMS list of MACs by state shows J6 covering Illinois, Minnesota and Wisconsin.

A MAC processes Medicare fee-for-service claims, enrolls providers and handles the first level of appeal. Medicare's filing limit is 1 calendar year after the date of service under 42 CFR 424.44(a)(1). On a dual-eligible patient Medicare goes first, and HFS accepts the crossover claim for up to 2 years from the date of service.

The same CMS table sends other claim types elsewhere: Illinois home health and hospice claims go to Palmetto GBA, and the DME MAC for Illinois is CGS Administrators (DME B). See our Medicare payer guide for appeal and enrollment steps.

What is Illinois's prompt pay law for insurers?

Under 215 ILCS 5/368a(c), Illinois insurers, HMOs, managed care plans, preferred provider organizations and third party administrators must pay health care claims within 30 days after receipt of due written proof of loss. Late payment earns interest at 9% per year from the 30th day after receipt to the date of payment, and interest under $1 need not be paid.

The plan must also tell the provider within 30 days of receipt about any known failure to provide enough documentation for a clean claim, and pay any interest within 30 days after the payment. The Illinois Department of Insurance (DOI) enforces the section. This wording comes from the compiled text of Section 368a on the Illinois General Assembly site, as amended through Public Act 97-813 (effective July 13, 2012).

Days count from receipt, so receipt is your evidence. DOI's provider complaint page asks for proof of the submission date: an electronic transmission confirmation, a certified mail return receipt, a provider mail log or courier delivery information. We keep the clearinghouse acceptance report for every claim for that reason.

DOI says the prompt pay law does not apply to self-insured employer plans, Medicare or Medicaid. A late self-funded claim follows the plan's terms and federal ERISA rules. For Medicaid managed care, the HFS portal above is the route. To complain to DOI about a fully insured plan, file online or by mail, in writing, with the patient's ID card, the CMS-1500 or UB-04 and proof you tried the payer first.

How does Illinois's surprise billing law work next to the federal No Surprises Act?

Illinois has its own surprise billing law for state-regulated health plans: Section 356z.3a of the Insurance Code, 215 ILCS 5/356z.3a. For a fully insured plan inside its scope, Illinois negotiation and arbitration apply instead of federal IDR. Self-funded employer plans follow the federal No Surprises Act and not Section 356z.3a.

DOI Company Bulletin 2022-13 (August 10, 2022) says Public Act 102-0901, effective July 1, 2022, widened the section to line up with the federal act. It now covers major medical PPO plans, HMO health care plans and comprehensive voluntary health services plans. It governs emergency services from nonparticipating providers and facilities, certain post-stabilization services, and non-emergency care from a nonparticipating provider at a participating facility when the service is an ancillary service as the statute defines it, arises from unforeseen urgent medical needs, or lacked valid notice and consent.

The patient's share comes first. The recognized amount is the lesser of the billed amount or the qualifying payment amount, cost sharing is applied as if the care were in network, and the patient cannot be billed more, whatever the status of the payment dispute.

Unlike the early federal IDR rules, the Illinois arbitrator does not start from a presumption that the qualifying payment amount is the right total, per 215 ILCS 5/356z.3a(e). The parties agree on an arbitrator from the DOI list. If they cannot, DOI supplies five names, the issuer and the provider each veto two, and the one left decides. Your evidence on the value of the service carries more weight.

Interest has its own rule after a decision. Under 356z.3a(g), the Section 368a prompt pay rule does not apply while the arbitration is pending. Once the arbitrator decides, Section 368a applies to the amount by which the award exceeds the issuer's initial payment, or to the whole award if the issuer denied payment at first. That interest does not start until 30 days after the decision, and in no case later than 150 days from the date the nonparticipating facility-based provider billed.

Some services sit outside the section. DOI says no Illinois law covers balance billing by out-of-network air ambulances, so the federal act applies. Ground ambulance for HMO enrollees falls under 215 ILCS 125/4-15(b), where a provider that accepts the HMO's payment agrees not to seek payment from the enrollee. CMS's applicability chart, current as of January 11, 2023, lists Illinois in its bifurcated process column, so we confirm plan type and service first. See out-of-network billing and IDR for the federal steps.

Which Illinois services does the state law reach?

Before July 1, 2022, arbitration under Section 356z.3a, effective June 1, 2011, covered radiology, anesthesiology, pathology, neonatology and emergency department services at participating hospitals and surgical treatment centers, per DOI Bulletins 2011-07 and 2022-03. Public Act 102-0901 widened that scope. Those lines still start most disputes: emergency medicine, anesthesia, radiology, pathology and neonatology. The statute text defines ancillary services as items and services related to emergency medicine, anesthesiology, pathology, radiology and neonatology provided by any health care provider; services of assistant surgeons, hospitalists and intensivists; diagnostic services such as radiology and laboratory work, except advanced diagnostic laboratory tests on the federal list; other specialty services the federal Secretary names by rule; and services from a nonparticipating provider when no participating provider can or will furnish them at the facility.

Which payers matter most for Illinois hospitals?

In DOI's 2024 Health Market Share Report, published May 2025, Health Care Service Corporation is the largest writer overall and in group comprehensive coverage, followed in group by United Healthcare Insurance Company of Illinois and Health Alliance Medical Plans. Medicaid plan names from the HFS list, such as Meridian, Aetna Better Health of Illinois and Molina Healthcare of Illinois, also appear among the largest writers. Humana, Care Improvement Plus and Coventry Health Care of Illinois lead the Medicare lines.

The report measures premium, not claim volume at your facility, so pull your own remittance data before choosing where to put effort.

What else is different in Illinois?

The Illinois Health Facilities and Services Review Board runs the state's certificate of need program under 20 ILCS 3960, regulating the planning, construction and operation of healthcare facilities. A hospital adding a service line should check the Board first. On claims, HFS takes the paper HFS 3797 for non-institutional Medicare crossovers and the UB-04 for institutional ones; our hospital and facility billing work checks bill type and patient status before release.

How does Illinois differ from Indiana, Wisconsin and Iowa?

Illinois shares its Medicare contractor with Wisconsin, since NGS holds J6 for both, but the Medicaid agencies, filing rules and plan lists differ. Indiana and Iowa have different Medicare contractors. See the state hub to compare.

How we handle billing in Illinois

For Illinois clients we confirm plan type first: fully insured under DOI rules, self-funded under the federal act, HealthChoice Illinois or HFS fee-for-service. Then we set the clock, whether that is HFS's 180 days, the 30-day issuer response under Section 356z.3a or the plan contract. Claims go out within 24 hours of charge entry and denials are worked within 48 hours.

When an Illinois out-of-network bill is underpaid, we prepare the arbitration or federal IDR submission and track every date. Want to talk through your accounts? Book a call.