By Anna Wilde Mathews And Dana Mattioli 

The federal government's release of new data on health-insurer payments under the Affordable Care Act is roiling the industry, including potentially affecting the timing of any deal for Humana Inc., as suitors pore over the detailed information disclosed late Tuesday.

The possible purchasers of Humana are taking into account how the payments would affect a potential tie-up and purchase price, according to people with knowledge of the matter. Aetna Inc. and Cigna Corp. have been sizing up Humana, which has privately offered itself for sale.

Broadly, big insurers and their advisers are digesting the numbers and what they mean for profits, say people familiar with the matter, amid a merger tussle with various alliances under consideration among the top five insurers by revenue. Some people noted the data, the first such release under the law, doesn't yet reflect a full picture.

Like some other insurers, Humana appears likely to receive considerably less than it had expected--around $426 million allotted for 2014, instead of about $628 million, according to Ana Gupte of Leerink Partners LLC.

Ms. Gupte estimated that this amount would translate into an approximately 7% dip in Humana's projected earnings per share for 2015. But she said the final impact isn't yet clear, and could be less, because the government calculations released so far aren't complete.

At issue are payments under government programs that are supposed to smooth out the risk for insurers that enroll a lot of less-healthy, expensive patients under the federal health law. The law has three programs that can provide financial help for insurers, largely funded by payments made by other insurers that had less-costly enrollees.

Late Tuesday, the Obama administration released calculations of payment amounts for 2014 for two of those programs. Until then, insurers had penciled in estimates of potential receivables and payables to complete their 2014 financial reporting. The third program's results haven't yet emerged, leaving insurers with remaining uncertainty. The federal report also notes its calculations don't include adjustments that might come due to factors including appeals.

Chris Rigg, an analyst at Susquehanna Financial Group, said it would make sense for a potential acquirer to dig into the new information regarding Humana. "You'd at least want to know what level of earnings you paid for."

Humana isn't the only major insurer that appears on track to get a different amount than it expected from the two programs disclosed so far. Aetna, for instance, appears set to receive around $70 million less than it projected, according to Mr. Rigg. He also said it appeared Cigna would be getting more than it estimated, though the exact amount of the overshoot wasn't clear.

Aetna said in a statement that the first year of the health-law programs was "a learning process." The insurer said it hadn't booked any receivables for the third, so-far-not-quantified program but now feels "it is logical to assume" that it might in fact get some payments.

Though the health-law programs can create bumps for such big companies, they matter far more for smaller insurers, particularly startups focused on plans sold through the health-law marketplaces. For some of those firms, the payouts may be a matter of survival.

The issue is the latest sign of the challenges for an industry that continues to face instability tied to the federal health law, five years after its passage. Indeed, deal-making largely paused over the past few years as health insurers digested the effects of many of the law's biggest provisions, which hit in 2014. Most recently, the law faced a Supreme Court challenge that could have made many of its insurance exchanges largely dysfunctional--which was only resolved in the Obama administration's favor last week, removing one big question mark.

Write to Anna Wilde Mathews at anna.mathews@wsj.com and Dana Mattioli at dana.mattioli@wsj.com

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