Effective Dates and Price Proration
This section describes how proration applies to different types of calculation rules. Proration implies assessing charges proportionately.
The term "proration" describes two different issues:
Prorating a charge whose value changes during a bill period. For example, if a tax rate changes during a bill period and you've indicated that such changes should be prorated, the system prorates the tax change (e.g., 20 days at 5% and 10 days at 6%).
Prorating charges when the time period being billed is not in sync with the time period in which the charges were defined in the rate. For example, if a rate contains a flat monthly charge and the bill period spans two months, the flat charge must be prorated.
This is a complicated topic as it's possible for many proration issues to exist on a single bill. For example, on a single bill:
The rate structure can change several times during the bill period (i.e., multiple rate versions are effective).
The taxing authority changes the tax rate.
The customer's tax exemption changes.
The customer-specific price can change.
etc.