Who leaves employer-sponsored insurance on the table?

The Kaiser Family Foundation's latest estimate of the still-uninsured population in the U.S. includes about 4.8 million whose employers offer health insurance that they decline to buy.

Some are locked out by the ACA's so-called "family glitch," which denies marketplace subsidies to those for whom an employer's insurance offering would cost less than 9.5% of income for individual coverage, even if the family coverage offered by the employer costs far more than that. But many low income workers find even individual employer-sponsored insurance (ESI) unaffordable. Probably the bulk of Kaiser's estimated 4.8 million who forgo ESI could do well in the ACA marketplace if the ESI offer didn't disqualify them from subsidies.

The New York Times' Stacy Cowley has a good story that spotlights the plight of those who can't afford insurance offered by their employers:

Why does the Census show such small gains among the poor in government-provided health insurance?

If I may reiterate: it seems quite strange to me that the Census health insurance surveys show a net gain for 2014 of just 1.3 million people with incomes under 138% of the Federal Poverty Level enrolled in government insurance plans -- whereas according to HHS, Medicaid enrollment increased by over 9 million in 2014, thanks to the ACA expansion. 138% FPL is the eligibility threshold for Medicaid under the ACA expansion.

The second half of this post provides more detail. According to the Census surveys, those with incomes under 138% FPL showed much stronger gains in private insurance than in public, while those in higher income brackets showed stronger gains in public insurance than in private. That's odd.

The difference may in large part be due to differences in how households are defined: the ACA marketplaces determine eligibility according to who is included in a household tax filing, while the Census surveys (CPS and ACS) consider who lives under one roof. Many other factors are in play, including a modest acceleration in Medicare eligibility and higher income thresholds for children in CHIP than for adults in Medicaid. But none appear on the face of things (as far as I can see) to explain the very low recorded gains in government insurance among adults under 138% FPL (and even more strikingly, under 100% FPL).

Again, there's more detail below the second subhead here (along with some updates added over the weekend). This post is simply to unbury the lead a bit, as I look into the state data.