Next Billing Date refers to the date/time on which a subscription will get renewed and the payment will get collected. In Chargebee, billing date/time is a subscription specific attribute: it will be based on the date/time of subscription activation and the billing frequency of the plan.
Sign up Date: Oct 1st (Monthly Plan)
Next Billing Date: Nov 1st Sign up Date: Oct 1st (Weekly Plan) Next Billing Date: Oct 8th Sign up Date: Oct 1st 2015 (Yearly Plan) Next Billing Date: Oct 1st 2016
When there is a trial period associated with a plan, the subscription will get activated only after the trial ends. In this case, the billing date/time will be based on the activation date/time.
Sign up Date: Oct 1st (Monthly Plan with 15 days trial period)
Activation Date: Oct 16th Next Billing Date: Nov 16th
The billing date/time of a subscription can be altered in following ways:
If you extend the subscription, then the charge is calculated as follows:
Charge = (Plan price ÷ Number of days in the plan billing period assuming plan starts from current date) x Number of days extended.
On the other hand, if you reduce the length of the subscription, credits are raised as follows:
Credits = (Plan price ÷ Total number of days in the current term of the subscription) x Number of days reduced.
The above calculation is done to the millisecond if the billing mode set for Chargebee is millisecond-based.