First, where it comes from. On July 24, the Congressional Budget Office sent a letter to House Speaker John Boehner, detailing the budget impact of repealing the Affordable Care Act. If Congress overturned the law, "spending for Medicare would increase by an estimated $716 billion over that 2013–2022 period."
As to how the Affordable Care Act actually gets to $716 billion in Medicare savings, that's a bit more complicated. John McDonough did the best job explaining it in his 2011 book, "Inside National Health Reform." There, he looked at all the various Medicare cuts Democrats made to pay for the Affordable Care Act.
The majority of the cuts, as you can see in this chart below, come from reductions in how much Medicare reimburses hospitals and private health insurance companies.
The blue section represents reductions in how much Medicare reimburses private, Medicare Advantage plans. That program allows seniors to join a private health insurance, with the federal government footing the bill. The whole idea of Medicare Advantage was to drive down the cost of health insurance for the elderly as private insurance companies competing for seniors' business.
That's not what happened. By 2010, the average Medicare Advantage per-patient cost was 117 percent of regular fee-for-service. The Affordable Care Act gives those private plans a haircut and tethers reimbursement levels to the quality of care administered, and patient satisfaction.
The Medicare Advantage cut gets the most attention, but it only accounts for about a third of the Affordable Care Act's spending reduction. Another big chunk comes from the hospitals. The health law changed how Medicare calculates what they get reimbursed for various services, slightly lowering their rates over time. Hospitals agreed to these cuts because they knew, at the same time, they would likely see an influx of paying patients with the Affordable Care Act's insurance expansion.
The rest of the Affordable Care Act's Medicare cuts are a lot smaller. Reductions to Medicare's Disproportionate Share Payments — extra funds doled out the hospitals that see more uninsured patients — account for 5 percent in savings. Lower payments to home health providers make up another 8.8 percent. About a dozen cuts of this magnitude make up the green section above.
It's worth noting that there's one area these cuts don't touch: Medicare benefits. The Affordable Care Act rolls back payment rates for hospitals and insurers. It does not, however, change the basket of benefits that patients have access to. And, as Ezra pointed out earlier today, the Ryan budget would keep these cuts in place.