Workers in volatile jobs are not, on average, working less than their stable counterparts. A study published in JAMA Network Open finds they are averaging at least 30 hours a week when employed. The problem is not hours worked but hours predictability, and that unpredictability is costing them employer-sponsored health coverage.
Researchers from Mount Sinai Hospital and the University of Michigan analyzed 2022 to 2023 Medical Expenditure Panel Survey (MEPS) data for low- and middle-income workers, those with household incomes at or below 400% of the federal poverty level. They tracked three types of employment volatility: income volatility, a greater than 25% year-over-year change in wage income; work-hour volatility, high within-person variation in weekly hours; and employment disruption, any transition from employed to unemployed between consecutive survey rounds.
The coverage gap across all three groups was substantial. Workers with income volatility were 14.9 percentage points less likely to be offered employer-sponsored insurance (ESI) than stable workers. Those with work-hour volatility were 14.4 percentage points less likely to receive an ESI offer. Actual ESI coverage was 19.6 to 24.1 percentage points lower across all volatile groups than among stable workers.
Volatile workers were correspondingly more likely to rely on Medicaid, by 12.2 to 18.9 percentage points, or the ACA marketplace, by 4.3 to 5.0 percentage points. The hour-tracking detail underneath those figures connects the study to benefits plan design. For income-volatile workers, 45.3% had hours that crossed above and below 20 hours per week across survey rounds, compared with 13.3% of stable workers. An employer whose eligibility threshold sits at 30 hours a week is looking at a workforce segment that routinely moves across that line.
The study was designed in part to anticipate the implications of House Resolution 1 (HR 1), enacted earlier this year, which conditions Medicaid eligibility on documented monthly work hours of 80 or more and introduces more frequent eligibility redeterminations.
Separate Hamilton Project analysis of low-income service workers found that nearly two-thirds of those workers, and more than one-third of those averaging 80-plus hours per month, failed to meet an 80-hour monthly threshold in at least one month of 2022. The JAMA authors argue that volatile workers risk Medicaid disenrollment not because they are not working, but because fluctuating schedules make documentation against a stable employment standard difficult.
The study draws on self-reported MEPS data, and the authors note that the concurrent unwinding of continuous Medicaid enrollment may affect the generalizability of the coverage findings. The ACA marketplace, historically the backstop for workers without ESI, is contracting as a fallback at the same time.
As coverage of the ACA subsidy expiration has documented, average out-of-pocket marketplace premiums rose 114 percent for subsidized enrollees in 2026, following the December 2025 expiration of enhanced premium tax credits, with roughly 3.2 million workers projected to shift toward employer-sponsored coverage as individual market costs became unaffordable. Volatile workers, already underserved by ESI, are poorly positioned for that shift.
The coverage gap the study documents is most concentrated in the sectors where advisers serving high-turnover accounts already operate: retail, food service, healthcare support, and light manufacturing. An employer in those sectors with workers whose hours routinely cross the plan's eligibility threshold is already managing the administrative friction the study describes. Under HR 1's Medicaid requirements, those workers now face losing their coverage fallback without a reliable path to replace it.
The plan design consequences show up at renewal. How an employer's eligibility rules interact with its workforce's actual hour patterns becomes a more consequential question when Medicaid is no longer available as a parallel safety net. Variable-hour employee classification, look-back measurement periods, and administrative period design - the standard tools for managing eligibility complexity in employer-sponsored health plans - now carry more weight than they did when Medicaid could absorb the workers who fell through the gaps.
"These findings highlight the importance of protecting coverage pathways for workers in volatile work arrangements with limited ESI access," the study's authors concluded.
