The federal website, his company, and the popular HealthSherpa.com corrected their programming after discrepancies were pointed out by an Inquirer reporter who discovered the issue while researching a Sunday Health section graphic that explains how the subsidies work.
It was "impacting no one's official determination when they applied for health coverage," said Aaron Albright, a spokesman for the federal Centers for Medicare and Medicaid Services.
But he was unable to answer concerns raised by health groups that people would simply not apply after learning from the window-shopping tool that they could not get financial assistance. The government encourages consumers to window shop before applying.
He also said he could not respond to criticism from health-policy experts that official letters of acceptance or rejection omit key details - such as what income amount was used - that would be needed to spot an error and appeal.
Subsidies for Marketplace insurance are linked to the poverty level, which is adjusted slightly every year to track inflation.
Households between 100 percent and 400 percent of poverty - $11,490 to $45,960 for an individual in 2013 - are eligible for tax credits that are applied immediately to lower the monthly premiums for private coverage.
Medicaid covers everyone below 138 percent of the poverty level in states, including New Jersey, that have accepted an optional Medicaid expansion. Like food stamps and other immediate-benefit programs, it uses the most recent poverty-level guidelines - those for 2014 were released in January - to determine eligibility.
The Marketplace, however, works more like commercial insurance, and the six-month open-enrollment period began Oct. 1. The Affordable Care Act requires determinations this year to rely on 2013 poverty guidelines.
Healthcare.gov's window-shopping tool used the new 2014 guidelines for both Medicaid and the Marketplace from Feb. 13 until sometime late Thursday or early Friday, shortly after learning of the problem, Albright said. He said he did not know why.
The most potentially problematic responses would have been to queries from people who live in the two dozen states that have not expanded Medicaid and who have household incomes above the 2013 poverty level and below 2014.
Brian Haile, a senior vice president for health policy at Jackson Hewitt, did some "back-of-the-envelope" calculations based on census data. He estimated that 70,000 uninsured in non-expansion states had incomes within that sliver. About 5,000 live in Pennsylvania.
All those states rely on Healthcare.gov. Fourteen others operate their own marketplaces. Those states expanded Medicaid, so any errors would result in minimal disruptions.
Still, "there may well be more states out there with this issue," said Jocelyn Guyer, a director at Manatt Health Solutions who worked with states to set up their own sites.
"I've spoken recently with some of the people charged with building the systems for the states, and they were just learning about the use of two different federal poverty lines," Guyer said Friday. "This is just the kind of important detail that was at risk of falling through the cracks."
Michael Wasser, a cofounder and one of the programmers for HealthSherpa.com, said his site had switched to 2014 guidelines shortly after they were released. The programmers realized a few weeks ago that the Marketplace was supposed to use 2013. A reporter's query "brought it to our attention again," he said Friday.
The site was fixed a little over a week ago. "For us, it was changing five numbers and running one line to redeploy the newest version," Wasser said.
Independence Blue Cross also posts an online calculator to help potential customers assess eligibility for subsidies, which then must be finalized at the federal site. Officials there, too, learned that it was inaccurate only after talking with a reporter. They said they quickly contacted Stonegate, which had created it.
Pierce, the executive at the Chicago-based firm, said he could not confirm clients' identities for confidentiality reasons. But he said calculators on eight client websites were updated Tuesday, "a simple change in a table that takes less than an hour to update and deploy."
How did the error get in there to begin with?
When the 2014 federal poverty-level numbers were released in January, Pierce said, "our analysts did some investigation and verification, and saw other calculators including Healthcare.gov's quick check calc was using 2014 FPL rates." Based on that research, he said, "we updated our rate tables."