[FlameThrower]

The difference: when billings exceed the retainer, you get charged the difference. This is exactly the issue raised by the doctor's service. If he gets more than the expected number of accidents or illnesses, he will go broke. And his patients will be left high and dry.

[PapaBear3625]

If he gets more than the expected number of accidents or illnesses, he will go broke. And his patients will be left high and dry.

Or he will have to change his rates, or not retain patients with chronic conditions (For this to work, the doc has to have the option of not renewing a patient who has a chronic condition at the end of the year).

For other patients, it is reasonable to assume that illnesses and accidents will be fairly evenly distributed over the year, and that this month's payments can be used to cover this month's expenses.