The savings come from the health-care reform bill's success in closing Medicare Part D's "doughnut hole"—the gap between basic and "catastrophic" prescription drug coverage that leaves some beneficiaries paying full price for their drugs for several months of the year.
The ACA has so far reduced the doughnut hole by about 25 percent. In the first six months of 2012, the Department of Health and Human Services has reported, price concessions from drug companies stipulated in the law have saved Medicare recipients an average of $629, and about $647 million overall. By 2020, the doughnut hole is expected to be closed completely.
"Those savings will continue to grow as the doughnut hole is fully closed," Jon Blum, director of the Center for Medicare, told USA Today earlier this year. (Read More: More Americans Working Until Medicare Kicks In)
For the moment, those savings are fairly modest, but enough for the researchers at the Employee Retirement Benefits Institute to subtitle their report on the implications of closing the doughnut hole "Rare Good News."
Most couples retiring now, the report said, will need to set aside 1 percent to 2 percent less for various Medicare and Medigap premiums and out-of-pocket drug expenses than the same couple would have last year, or about $163,000 versus $166,000, if they want a 50 percent chance of covering themselves through retirement.
The more drugs you use, the more you can plan on saving: A couple in the 90th percentile for drug spending can now anticipate needing 4 percent to 5 percent less than they would have to have on hand last year—or about $234,000 to have a 50-50 shot at their covering drug expenses. (Read More: When - and How - to Take Social Security)
Such incremental savings may be scant relief for those who are behind on their retirement savings—and that's most Americans, according to the Federal Reserve. Obamacare's savings could also be reduced at any time, if the pharmaceutical companies begin to pass along to consumers the cost of lowering their prices.
But for now it looks like the savings will snowball and the sticker shock of what it takes to retire comfortably will be softened as the doughnut hole closes over the next eight years.