Too sick to work? States must get their new Medicaid rules right.

Starting Jan. 1, 2027 , Illinois will ask adults in its Medicaid expansion program to either prove they worked 80 hours in the last month or that they are too sick to work. The state will answer that second question mostly with billing codes.

For a woman between an abnormal mammogram and a confirmed diagnosis, the billing codes say she is fine. Her doctors do not.

Congress set the requirement. States decide how to run it. The hardest decision is how you tell from a claims file who is too sick to work. On July 30, a federal judge declined to pause the rule while a multistate challenge proceeds. States are building their systems now — Illinois shows what is at stake in getting it wrong.

The law exempts people who are “medically frail,” a category meant to protect those with conditions that keep them from working. Cancer treatment can qualify, for example. The problem is how states find those patients.

Illinois, like most states, will lean on claims data, the billing codes generated when patients receive care. Those codes work well for a patient mid-chemotherapy, but they fail at both ends — both before a diagnosis is confirmed and after treatment ends while monitoring continues.

An abnormal mammogram creates a patient before it creates a diagnosis. Between the image and the pathology report, she moves through more imaging, a biopsy and specialists. The cancer code belongs to the end of that process. Until pathology confirms malignancy, the record holds only fragments: screening, abnormal finding, follow-up.

That is not how she experiences the interval. She is not waiting for a code. She is waiting to learn whether the shadow on the image is cancer.

If her Medicaid renewal falls in that window, the system reads the absence of a confirmed diagnosis as the absence of a serious condition. She has no diagnosis that qualifies her for an exemption. The record isn’t merely behind her illness, it is governing her access to care before the illness exists on its terms.

There’s a second trap, and it’s worse. Illinois covers breast and cervical cancer treatment through a separate Medicaid category , but the state’s own rules are explicit that people already eligible for Medicaid cannot receive benefits under it . A woman already enrolled through the expansion doesn’t move into that pathway when she’s diagnosed. She stays in the expansion group, subject to the work requirement, through surgery and chemotherapy. The exposure isn’t a gap of a few weeks before diagnosis — it’s a standing condition that lasts the length of her treatment.

Arkansas already ran this experiment. In the first seven months of its 2018 work requirement, about 18,000 people lost coverage , a full one in four of those subject to it. A study in the New England Journal of Medicine found employment did not rise. People lost coverage because they couldn’t navigate the reporting, not because they weren’t working. By early 2019, only about one in 10 had gotten it back.

The federal law is settled. The implementation isn’t, and states are already choosing differently: screening for medical frailty at application, building hardship exemptions, setting longer compliance periods. Illinois doesn’t need to redesign federal policy to protect these patients. It needs to decide where it puts the burden of proof.

What would protecting them look like? States could shield patients from the moment they get abnormal screening results, so they are not asked to prove they are sick during the weeks the record cannot yet show it.

States could add a grace period when a diagnosis is documented but the claim has not yet caught up. They could accept a letter from free or community clinics that don’t bill Medicaid, so the poorest patients aren’t invisible. They could keep survivors covered while they are still being monitored.

None of that changes the federal requirement; all of it is within the states’ power.

The Centers for Medicare and Medicaid Services itself projects that 2.3 million people will lose Medicaid in the first year. No vote in Springfield will revisit the federal law. But in administrative offices over the coming months, officials will decide which diagnoses count, when exemptions begin, and how much proof patients must produce before the system believes they are sick.

Cancer doesn’t wait for a billing code to catch up. Neither should the states now deciding what counts as proof of illness.

Akshaya Sahasra Ganji is an undergraduate health policy researcher at Florida International University in a combined medical degree program. Her research focuses on women’s health, neuroscience and health policy.