Advocates for patients argue this retroactive coverage, as it is known, is a crucial safety net that saves the uninsured from debt.

The state Human Services Department says about 10,000 low-income New Mexicans applied last year.

But department officials propose to scrap the policy. They argue retroactive coverage is increasingly unnecessary as the number of New Mexicans without health insurance falls thanks to the Affordable Care Act, also known as” Obamacare.” And the policy can seem counterintuitive at a time when federal law requires virtually everyone get health insurance.

Still, advocates for patients who may be most likely to slip through the cracks of the health care system argue that ending retroactive coverage threatens to saddle patients with debt and stick doctors and hospitals with unpaid bills.

“There are still folks out there in New Mexico who qualify for Medicaid and aren’t receiving it,” said Lisa Huvel, associate director of the New Mexico Coalition to End Homelessness. “It’s a lot easier to get it than it used to be but it’s not automatic.”

The Human Services Department is expected to propose an end to retroactive coverage later this month when it sends the federal government a plan for overhauling New Mexico’s Medicaid program that also includes charging new copayments and premiums for many.

Gov. Susana Martinez expanded access to the health care program for low-income people in 2013 under the Affordable Care Act and enrollment has ballooned in a state that continues to have one of the highest rates of poverty in the country. In January 2013, fewer than 600,000 people were enrolled in Medicaid. By August 2017, nearly 912,000 had signed up, though the number appears to have flattened. Still, as of 2016, 11 percent of New Mexicans did not have health insurance, one of the highest rates in the country.

In a draft of the proposal for what it calls Centennial Care 2.0, the Human Services Department says retroactive coverage will be less necessary not only because more people have health care coverage but because it will also launch a system next year to determine virtually in real time whether applicants are eligible. So a hospital patient who does not have coverage can enroll and know whether they will be covered almost immediately. And as the state government’s costs for running Medicaid continue to rise, the department argues this would eliminate what can be a complicated process of reconciling old bills.

Native Americans and people living in nursing facilities could still be eligible for retroactive coverage.

But a seemingly unlikely group of big hospitals and patient advocates argue that does not erase the need for the policy.

The University of New Mexico Hospital has asked the state to keep the policy in place, noting in a letter to the Human Services Department that trauma patients may not be able to sign up for insurance before receiving care in an emergency.

And Huvel said that while hospitals may be able to enroll uninsured patients in Medicaid and even connect them with other services such as housing, adding debt on top of that would be a setback rather than a leg up for many.

Meanwhile, some doctors warn that ending retroactive coverage will leave them with more unpaid bills.

“Many practitioners throughout the state also agree to see patients without Medicaid being fully in place knowing that coverage is retroactive,” the New Mexico Pediatric Society said in a letter to the Human Services Department. “Loss of retroactive Medicaid would likely result in large losses to hospitals, health systems and private practitioners.”

In fact, hospitals have been among the staunchest critics of ending retroactive coverage in other states, arguing they will be on the hook for more care that patients cannot afford to pay.

At Albuquerque Health Care for the Homeless, Executive Director Jennifer Metzler said retroactive coverage appears to have given hospitals an incentive to enroll patients who do not have coverage.

“There’s an incentive to them and the result is more people are insured,” she said.

A spokesman for the Human Services Department did not respond to a request for comment or make anyone available for an interview.

But under the administration of President Donald Trump, the federal government seems more open to the idea of ending retroactive coverage.

Most recently, Iowa announced it would scrap retroactive coverage after officials sold it as a means of curbing costs.

Arkansas, Indiana and New Hampshire have at least partially ended retroactive coverage.

Last year, Seema Verma, who is now chief of the federal Centers for Medicare and Medicaid Services, argued such a benefit is counter to the very ideas that led states to expand access to health insurance for adults with low incomes.

“Especially in a world where all Americans are required to comply with an individual mandate to purchase health insurance, retroactive coverage in Medicaid represents a policy conflict,” Verma said in an article she co-authored last year for the journal Health Affairs.

Verma and her co-author, Brian Neale, argued that eliminating retroactive coverage is a logical part of efforts to encourage patients to get covered, stay covered and manage their own care.

Critics are not convinced the state is ready, however.

“Real-time eligibility will be great. I hope and pray for real-time eligibility,” Abuko Estrada, a staff attorney at the New Mexico Center on Law and Poverty, told a legislative committee in September. “There are going to be situations that fall through the cracks and we are going to need this safety net to save families from medical debt.”

Contact Andrew Oxford at 505-986-3093 or aoxford@sfnewmexican.com. Follow him on Twitter @andrewboxford.