In the US, how hard it is even for your insurance company to figure out if a doctor/hospital/etc. is in or out of their contracted network.

You'd think "how hard can it be, you either signed a contract with them and have it on file, or not". Well...

When the insurer signs a contract with, say, a doctor, what is happening is not "anything this doctor does for someone on one of our plans is covered by this contract". Instead, whether something falls under the contract or not depends on a whole bunch of factors, including but not limited to:

* The doctor's NPI (provider identification number, issued by US Medicare/Medicaid).

* The particular medical specialties and credentials of the doctor.

* The location(s) where the doctor renders services and the type(s) of services rendered.

* The federal tax identification number and billing entity the doctor bills as.

* The address the doctor submits on the bill.

So suppose Dr. Jane Doe signs on to your insurer's network. She's contracted as a primary-care physician, rendering services in her office at 123 Main Street Suite B, under NPI 1111111111, and will bill as Jane Doe Medical, tax ID 222-22-2222, payment to be sent to her billing office at 234 Second Street.

And you go to Dr. Jane Doe and have no trouble, until one day you get a notice back from your insurance company that suddenly she's no longer in network. She swears up and down that she's still in network with them, so it must be the insurance company's fault, right?

Well, the thing is that she merged operations with Dr. John Roe in the next office suite over, and now is billing as Doe & Roe Medical, tax ID 333-33-3333, payment to be sent to 345 Elm Avenue. And there's no contract for that!

Or she outsourced all her medical billing to MedBillCo, which again changes information the contract is keyed to. Or she also holds credentials for other types of medical practice and was rendering service of that type, maybe at a local hospital. Or she kept her tax ID and billing the same but moved her office from 123 Main Street Suite B to 123 Main Street Suite C. Or the post office realigned the boundaries of her zip code, and she "moved" from zip 11111 to zip code 11112 as a result.

This sort of thing happens all the time.

I'm told that LexisNexis once came to an (I think optimistic) estimate that the half-life of medical provider data is 18 months. So gather up all the information on your network of doctors and hospitals, carefully vet and double-check it, make sure everything is full and correct and up-to-date... and 18 months later half of it will be wrong, just due to the background rate of changes to office locations, credentials, billing entities, etc.

So after working for a little over a year at a company that has to deal with this, I am not surprised at all when I hear someone complain that "it's the same doctor I went to last time, nothing changed, they're still in network, so why can't the insurance figure that out?" Nothing visible to the person complaining has changed, sure. But that tells you nothing. I am more often surprised that anyone is ever able to correctly determine in- or out-of-network status; being able to do it even a fraction of the time is frankly a minor miracle, and requires a whole lot of people toiling away behind the scenes.

For the record: I work for a company in the Medicare space, and we're required to revalidate all our provider information at least once every 90 days, precisely for this reason. Also, you don't want to know what the industry average is for correctness of printed provider-directory booklets. Even if it's sent off to the printers the day the up-to-date data has been validated, some not-insignificant proportion of it will already be wrong by the time it arrives in someone's mailbox, just because of how often and how quickly the information changes.