Republicans have found a new part of Obamacare they think is illegal

House Republicans filed a lawsuit today challenging the legality of how the White House has implemented Obamacare. This is not a surprise: House Speaker John Boehner (R-OH) has been pursuing this case for months now.

But there is at least one unexpected feature of the House Republicans’ suit against Obamacare, which you can read here: alongside the challenge to the employer mandate, it also argues that the White House is also breaking the law by giving insurance companies money that hasn’t been appropriated by Congress.

The government makes these payments to insurance companies for a little-known program called “cost-sharing reductions.” These are subsidies that low-income people get to help cover the out-of-pocket costs above and beyond monthly premiums. Cost-sharing subsidies are used to cap how much Obamacare enrollees have to pay for co-payments, co-insurance, and other forms of cost-sharing.

The limit is on a sliding scale by income, so someone right at the poverty line would be expected to spend no more than $2,250 on out-of-pocket insurance costs. The cost-sharing reduction would kick in to cover anything above and beyond this. You can see how the cost-sharing limit goes up with income in this chart from the Kaiser Family Foundation.

The federal government pays the cost-sharing subsidy directly to the insurance plan. So if, for example, someone right at the poverty line had $3,000 in out-of-pocket costs, she would pay $2,250 — and the government would send along the other $750.

This is the money that the House is challenging in this new lawsuit.

While the Affordable Care Act authorized these cost-sharing subsidies when it was passed in 2010, the House lawsuit says it never appropriated the necessary funding to be sent over to Health and Human Services. Here’s the relevant bit of the lawsuit on this issue:

Later, the lawsuit argues that “the House has been injured, and will continue to be injured, by the unconstitutional actions of defendants Lew...which, among other things, usurp the House’s legislative authority.”

If House Republicans protesting payments to health insurers sounds familiar, it’s because it happened this past winter — but those were a completely different part of the health care law.

Back in January, Republicans began sharply criticizing a so-called “Obamacare bailout” that transferred federal funds to private insurance companies. The bailout typically described three programs in the health care law — risk corridors, risk adjustment, and reinsurance — that make it less financially risky for insurers to participate on the Obamacare marketplaces.

These programs are really different from the cost-sharing reductions because they aren’t tethered to any one enrollee’s cost. They’re paid out to insurers as a lump sum, mostly depending on if the health plan got stuck with really expensive, sick subscribers.

The cost-sharing subsidies are tethered to how much an insurer’s enrollee earns, not how high their health care costs are. And if the Republican lawsuit succeeds, it would mean the federal government can’t send payments to insurance plans to keep lower-income enrollees’ out-of-pocket spending lower. Insurers would still, however, have to adhere to those limits — essentially leaving them to cover some of their poorer members’ co-payments and co-insurance rather than the federal government.

Correction: An earlier version of this article said that the Republican lawsuit was challenging the the cost-sharing limits in Obamacare. It is challenging the subsidies that the the White House has administered to keep consumers under those limits, but not the actual cost-sharing caps themselves.