how do deductibles work with health insurance?

I am not sure i understand how the deductible works with health insurance plans, can someone expalin to me how it works.
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I will try to explain. Your deductible starts over each year. So say you have a $2,500 deductible, any medical treatment you have in a year that cost less than $2,500, you have to pay out of pocket yourself. So if you go to the doctor, have lab work done, etc and the total amount of your bills total $450, you will pay since less than the $2,500 deductible. But say you have surgery and the cost for it is $6,000. Then you pay the 1st $2,500 and then that leaves a balance of $3,500 owed. At that point the insurance pay this and any other bills you may have in the year will be paid by the insurance company since you have met your deductible. But here is when it gets confusing. Since most policies have a co-insurance clause which is usually around 80% (80/20), then of the $3,500 the insurance owes, you may owe an addtl 20% of that amount. So the insurance would pay $2,800 of the bills and you would pay $3,200 of the $2,500 deductible and $700 for the addtl 20%. hope that makes sense. good luck
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