Patients will soon have a clearer picture of what insurers and employers pay for health care thanks to a federal rule that kicks in today — if a collection of health tech companies can make the trove of data understandable.

Why it matters: Patients often have no idea what a procedure or service costs — and have little ability to comparison shop — until they're left holding the bag with a higher bill than they expected.

Driving the news: Starting today, insurers will have to list their negotiated rates with in-network providers, as well as out-of-network allowed amounts and billed charges for certain items and services.

• It's part of a Trump-era price transparency rule that also required hospitals to start posting negotiated rates in 2021 (although many hospitals have been slow to comply.)
• Enforcement of the payer version of the rule was delayed until July 1, 2022. Insurers who don't release the info will face a penalty of $100 per person per day per violation.

What they are saying: "It's like the biggest milestone in U.S. health since the ACA was rolled out. It's massive what's about to happen," said Chris Severn, co-founder and CEO of Turquoise Health, a San Diego-based tech start-up that works with price transparency data.

• "On all these insurance company websites, in all of these files, the real price of health care is coming out. Not just for hospitals, but for all types of services," Severn told Axios.

Behind the scenes: There are a number of tech companies, like New York-based Ribbon Health — which just launched a partnership with Turquoise — eager to get their hands on this massive trove of machine-readable files to translate it for use by consumers.

• "This is a huge moment for the industry," Nate Maslak, co-founder and CEO of Ribbon Health told Axios. "We've finally hit this moment in time where this can be accessible."
• While some consumer price comparison tools exist, including on some insurer and provider websites, the numbers don't always match, and some tools only offer potential ranges of prices or are based on historical claims data which can be outdated.
• "I think for a long time we just kind of said: This is just impossible. I guess we'll just have to live with it," Maslak said. "In no other industry would we do that. Ever. I can't imagine going to a restaurant and saying: 'Well, this chicken might be $30 or $400 and we'll just have to find out.'"

Be smart: This push for price transparency has been years in the making, it'll probably take a while to impact the average consumer.

• The idea of shopping for a CT scan online has obvious appeal, but health care is filled with unfulfilled, tech-driven promises.
• Some researchers like Harvard's Amitabh Chandra also assert that consumers just aren't as inclined to shop for health care the way they would for a car or cell phone.
• Tech tools will likely start by offering more directional information such as offering an idea of where patients might save the most money on their care, "We're at the very first inning," Maslak said.

Reality check: While tech companies will have access to a lot of data, the law didn't require payers and providers to work together to define what a total episode of care means, said Seth Cohen, president at Cedar, a New York-based tech company that syncs payer and provider billing.

• "You look up a hip replacement. Does it include anesthesiology? Does it not? Do we have any post-care or follow-up? Or no post-op? Even if [the payer and provider] both display hip replacement, they can display wildly different prices."
• And while the idea of price transparency is aimed at driving down costs by allowing consumers to shop, it could actually drive up prices.
• "I don't know about you, but I don't like shopping for the cheapest doctor," Cohen said. "It's like buying a bottle of wine. I don't want to be the guy who chooses the cheapest bottle of wine on the menu."
• But Cynthia Fisher, founder and chairwoman of PatientRightsAdvocate.org said the price transparency shifts the power not only to patients, but to employers.
• "It's the empowered consumer and the empowered employer and union that are going to drive these costs down because they aren't going to tolerate any longer being overcharged once they see the data and are able to easily parse it," she said.

What to watch: The next step is the AI-driven tech tools getting better at predicting bundles of care that often occur together, Severn said.

Ultimately, the goal is total accuracy, he said. "Pre-packaged, upfront prices that do not waver at all in your encounter," he said. "You pay upfront and you're done. You'll never see another bill."

• "I can't wait in the next couple of years when the patient is spoiled and that's what they expect."