Deductibles 

The deductible is the amount that the patient must pay at the beginning of a new year before insurance will begin to pay. This is typically $50 and does not apply to preventive treatment. So a typical exam, xrays, and cleaning would be covered at 100%, and the patient would pay nothing. Then, when they come in for fillings, they would owe the $50 deductible at the first appointment. They would owe another $50 the first time they have treatment performed in the next benefit year.

The deductible always gets applied before the percentage is calculated. For example, if you have a $100 filling covered at 80%, the patient portion would be 50 + (50 * .2) for a total of $60. Note that this is not what some people expect (20 + 50). The patient will only have to pay an additional $40 even though they may expect to have to pay $50.

In older versions of Open Dental, there was a choice as to whether the deductible would be applied before or after the percentage.  But we now follow the industry standard and just calculate it one way.