Co-Pay: think going in on something with someone; "You pay $15 up front, and I'll cover the rest later".
Deductible: Most places, Co-Pay has nothing to do with deductible. For instance, I visit the doc once a month (and pay my co-pay, get my perscription refill, go get my meds, and wait 29 more days). However, I had to get an MRI about a week ago and imaging/radiology has a deductible ($250 in my case). Since I had nothing else in the imaging/radiology department, I had to pay my deductible. Just like with car insurance, if you are in an accident, you pay your deductible and they take care of the rest. After your deductible is met (and UN-like car insurance,) you start doing a co-pay on that service (most places).
Out-of-Pocket: Most places have a maximum out-of-pocket expense you can incur (co-pays don't count towards it, prescriptions don't either, and many places don't count deductibles...) and likewise a maximum coverage amount you're screwed if you go over. For instance, your maximum out-of-pocket may be $5k. If you end up with $10k in hospital stay expenses, the $5k after you pay the first $5k will be handled by insurance.
The problem is, every place handles it differently, and you have lawyers and legal people involved, etc. etc.
I once had insurance where you straight paid everything until you hit $2500 and then you got into co-pays and deductibles and stuff. It's a big ******* mess. I hope that vaguely helped.
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Since 1 March 2004 [riftsig]308642[/riftsig]