How to bill for a package offered based on hours of labor used

[jokermedia]

Hey all:

 

Wondering if anyone would know a good way to bill for the following:

 

We offer a package that is billed quarterly and clients are given an hour of labor per month under the package. if they use more than the hour of labor, they are charged the difference at our hourly rate. If they go under, they still pay the same package price.

 

We're trying to find a way to automate the system so when we enter in a billable item and it reaches more than an hour of labor any given month, it is somehow automated to bill the additional time with the package price.

 

Sounds difficult, but hopefully it's clear.

 

Thanks for any help!

 

 

JB