your scenario is either worded incorrectly or very atypical (which is very possible, there are a lot of different insurance plans in the us

typically high deductible plans work in a way of “meet your deductible and then we cover x% after that”

eg I am a therapist, I bill your insurance $100 for an hour session. You have a $1000 deductible with 80% coinsurance.

Our first 10 sessions will cost you $100 out of pocket, which goes to me directly. I submit billing for these sessions but get no reimbursement from the insurer because you have already paid the full amount. However, my submission of billing indicates to the insurer that you paid $100 for a medical service on whatever date for whatever diagnosis.

After the $1000 deductible is met your insurance splits the bill with you 80/20. Now you pay me $20 per meeting and when I submit the billing the insurance (hopefully) pays the other $80 to give me the $100 per meeting I am owed.

This of course assumes no other medical spending goes on for the duration, otherwise you would hit your deductible faster. If you saw me 3x and then had a surgery that cost $5,000, you’d pay $700 for the surgery to settle your deductible plus an additional $860 (20% of the remaining $4300) and then sessions would be $20 under the 20% coinsurance.

You should also have an out of pocket max, this is kind of similar to a deductible but it is different. This is a tally of your total spending and once you hit it your coinsurance usually drops and you pay nothing.

Also important point is that deductibles reset every plan year. This should have been made abundantly clear to you but I still encounter many who do not know this

Additionally your insurance may have certain services covered that don’t cost you anything or where the deductible doesn’t apply (eg you’d only pay 20% even if it’s the first appointment of the year). Typically this is preventative care, things like physicals and vaccinations

That is the most typical. But like I said it there are many plans and variations. It’s possible you have a plan that prior to meeting the deductible you pay 50% of billing and then have a 0% coinsurance. This would be really great insurance.

It’s also possible that you have a benefits package from your employer that is basically paying 50% of your deductible in a roundabout way. this is far more commonly done by the employer funding an hsa/fsa account which would be a payment card that you use on medical spending and not the insurer. However, I have encountered plans where the hsa and insurance were rolled together and joint companies, where the hsa would pay all or part of billing prior to deductible on the patients behalf

Using the same examples above you’d pay me $50 until you met your deductible, then nothing once the deductible is met. If you had a $1000 deductible, saw me twice, then had the 5k surgery you’d pay me $100 and $900 for the surgery. If you have one of the situations where the employer is covering 50% of the deductible it would be the same but the surgery would be $400 because ultimately you’re only paying $500 of the $1000 deductible and your employer is covering the other half. This is not a situation I’ve ever encountered

Another important point is that deductible status is dependent on your providers doing timely billing and your insurance processing said billing in a timely manner as well. This does not always happen. As a result you may meet your deductible but my billing verification shows that is not the case. The examples I used above were clean and easy but it’s never that simple. Most people have a deductible around $2500 (and many 2-4x this) and see several different healthcare services.

I submit my billing at the end of each day but some places are sloppy and will take weeks to submit. This can lead to situations where you are charged money because I was under the impression you had a deductible but you should not have been. Eventually the insurer will pay me once things sort out. If I am good at record keeping (I am great at it for this reason) I will catch the double payment and send you a refund. This is why it is important for you to keep track of deductibles and medical spending. Not all offices are managed well. I’ve personally had money stolen from me (because this is literally fraud, to not refund the double payment) and I don’t believe it was ever intentional, just offices with shitty management. Let your providers know if you’ve met your deductible. I will always hold off on charging you if you tell me this, submit billing, and see what the insurance reimburses. If they reimburse me in full then you were right. If they don’t I send you a bill and if that is incorrect you need to call your insurance to complain

You should be able to track deductible and out of pocket spending on your insurances consumer portal (eg go to Aetna.com or whatever and click “for subscribers” and make an account, if you haven’t already). This should also give you an explanation of plan details.

Most importantly you should be able to call the office of the place (or billing dept if it’s a larger health network) doing the procedure to have their office manager check what you will be expected to pay for the procedure both at time of service and expected cost total. This takes only a minute but be forewarned it is essentially an estimate and not a guarantee. Billing can change last minute depending on how the procedure goes (eg added complexity allowing them to add another cpt code for something)

There’s a lot more to it than this unfortunately. Some plans have tiered deductibles, sometimes a staff member in a hospital isn’t personally enrolled and then are considered “out of network”, which is a whole other thing, sometimes you are still responsible for a certain services that the provider requires but the insurance refuses to pay. That last point especially: every time you establish with a medical office or get a procedure you sign something that says you are financially responsible for services not covered by insurance (I guarantee this, every time). So if you get bloodwork with like 30 tests and 2 aren’t covered even if you’ve met your out of pocket max and have the best insurance in the world you’re getting a bill (and potentially a hefty one, some blood tests are extremely expensive)

Sorry this is very long and complex but that is kind of how insurance is? To boil it down to a “eli5” 2-3 sentence explanation would either require your specific plan information in much more detail or to overgeneralize and potentially mislead you.