Illinois gives physician practices strong payment protections on paper: insurers have 30 days to pay, late claims earn interest, and credentialing has a 60-day deadline. Getting the benefit of those rules takes work. Medicaid accepts only electronic claims, every ordering and referring clinician has to be enrolled, and 2026 brought a new state-run insurance marketplace. Personal injury claims are often paid through liens rather than insurance. Maximum Billing handles medical billing for Illinois physician practices and specialty groups, from Chicago and its suburbs to Springfield and downstate.
We bill for Illinois practices as part of our twelve-state service area. Schedule a consultation or call 800-820-0364.
Illinois Medical Billing at a Glance
- Prompt pay: 30 days after the payer receives proof of the claim, with 9% annual interest on late payments.
- Surprise billing: a state law for fully insured plans, with payment disputes resolved through the federal arbitration process.
- Medicaid: run by Healthcare and Family Services, with IMPACT enrollment, electronic claims only, and 180 days to file.
- HealthChoice Illinois: the state’s Medicaid managed care program.
- Medicare: National Government Services, Jurisdiction 6.
- Credentialing: a uniform state form and a 60-day deadline.
- Workers’ compensation: 30 days to pay, 1% interest per month, and mandatory acceptance of electronic bills.
Prompt Pay Under 215 ILCS 5/368a
Illinois requires insurers, HMOs, PPOs, managed care plans, and third-party administrators to pay claims within 30 days after receiving proof of the claim. If documentation is missing, the payer has to say so within 30 days. Late payments earn interest at 9% a year from the 30th day, and that interest has to be paid within 30 days of the claim payment. The same rules apply to independent practice associations and physician-hospital organizations that pay physicians. We track claim receipt and payment dates, so payers that run late are followed up and the interest is collected.
Surprise Billing in Illinois
Illinois’ balance billing law, 215 ILCS 5/356z.3a, covers emergency services and care from out-of-network providers at in-network facilities. Patients owe only what they would have paid in network, and balance billing above that amount is not allowed. Emergency medicine, anesthesiology, pathology, radiology, and neonatology services cannot be moved out of these protections by a notice-and-consent form. For fully insured plans, a payment dispute not settled within 30 days of the explanation of benefits can go to binding arbitration under the federal No Surprises Act process. Self-insured employer plans are governed by the federal law itself. The section was most recently amended effective January 1, 2026.
We sort out whether the state or federal process governs each out-of-network claim before it goes out. Our out-of-network billing services page has more.
Illinois Medicaid and HealthChoice Illinois
- IMPACT enrollment: every billing, rendering, ordering, referring, and prescribing provider must be enrolled through IMPACT. A claim can deny because the clinician who ordered a test was not enrolled, even when the billing provider was.
- Electronic only: Healthcare and Family Services has not accepted paper claims or attachments since December 15, 2021. Claims go through the MEDI system or an electronic upload.
- Timely filing: the 180-day limit runs from the date of service and covers resubmissions as well as original fee-for-service claims. For new or updated enrollments, the 180 days start when the record is entered in IMPACT.
- HealthChoice Illinois plans in 2026: Aetna Better Health of Illinois, Blue Cross Community Health Plans, Meridian, and Molina statewide; CountyCare in Cook County; and YouthCare for youth in care and former youth in care.
Each managed care plan is contracted separately, so a practice can be enrolled with Medicaid and still be out of network with a patient’s plan.
Medicare, Commercial Plans, and Get Covered Illinois
Original Medicare claims in Illinois go to National Government Services, the Medicare Administrative Contractor for Jurisdiction 6, which also covers Minnesota and Wisconsin. About a quarter of Illinois Medicare Advantage enrollees are in employer or union group plans, one of the highest shares in the country, so a retiree’s coverage often runs through a former employer’s plan.
For plan year 2026, Get Covered Illinois became a full state-based marketplace, and Illinois residents now enroll there instead of on HealthCare.gov. Patients who changed plans during that switch need their coverage verified again. State employees are covered through the State Employees Group Insurance Program, which offers HMO, open access, and PPO options.
Workers’ Compensation and Personal Injury
- Workers’ compensation: bills that include substantially all required data must be paid within 30 days. If a bill is incomplete or denied, the payer has to send an explanation within 30 days. Unpaid amounts earn 1% interest per month. Employers and insurers have been required to accept electronic bills since 2012.
- Fee schedule: payment is the lesser of the charge or the fee schedule unless a contract says otherwise. The schedule uses geographic regions and is adjusted every January. Providers cannot bill the injured worker unless the employer denies the claim, and must stop collection once a claim is filed with the Commission.
- Auto and personal injury: Illinois is a fault state, and medical payments coverage is optional. Under the Health Care Services Lien Act, providers can place a lien on a patient’s injury claim, but all liens together are capped at 40% of the recovery.
Credentialing Illinois Physicians
Under the Health Care Professional Credentials Data Collection Act, Illinois uses a uniform credentialing form set by the Department of Public Health and a single credentialing cycle. Plans must finish credentialing within 60 days after all credentials data has been submitted and verified. That clock does not start until the application is complete, so a missing document can cost weeks.
We handle CAQH profiles, Medicare enrollment through PECOS, IMPACT enrollment, and HealthChoice Illinois and commercial plan applications. More detail is on our medical credentialing page, and groups with several clinicians can see group practice billing.
Where Illinois Medical Claims Go Wrong
- Medicaid claims denied because an ordering or referring clinician was not enrolled in IMPACT.
- Claims or attachments sent to Medicaid on paper.
- Medicaid claims filed after the 180-day limit, including resubmissions.
- Patients who moved to Get Covered Illinois plans in 2026 but were seen on old coverage.
- Workers’ compensation patients billed directly when the law does not allow it.
- Late payments never checked for the interest Illinois requires.
Our claims denial management and accounts receivable management services cover how we recover them.
What Our Illinois Medical Billing Includes
- Eligibility and benefits checks for commercial, Get Covered Illinois, HealthChoice Illinois, Medicare, and Medicare Advantage patients.
- Coding review and claim submission, with clearinghouse rejections corrected.
- Posting of every payment, checked for late-payment interest and short pays.
- Denial follow-up and appeals.
- Credentialing, IMPACT enrollment, and enrollment updates for every clinician and location.
There is no need to change software: we log in to the system you use now. Every client signs a Business Associate Agreement with us, and our whole team is HIPAA certified. Our clients’ 2026 numbers are a 91% clean claim rate and an average of 34 days in accounts receivable.
Illinois mental health practices can see our Illinois behavioral health billing page. For practices in our other states, see our national medical billing services page.
Frequently Asked Questions
How fast do Illinois insurers have to pay a claim?
Within 30 days after receiving proof of the claim, under 215 ILCS 5/368a. Late payments earn 9% annual interest.
What is the timely filing limit for Illinois Medicaid?
180 days from the date of service for fee-for-service claims, including resubmissions.
Does Illinois Medicaid accept paper claims?
No. Healthcare and Family Services has required electronic claims and attachments since December 15, 2021.
How long does credentialing take in Illinois?
Plans must finish within 60 days after a complete application has been submitted and verified.
Start With an Illinois Billing Review
If Medicaid enrollment, late payments, or payer rules are costing your practice money, we can start with your aging report and your most recent denials and show you what is still collectible. Contact us or call 800-820-0364.