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.

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.

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.

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

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.

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."