There are several time-based methods for calculating rebates. This page explains about monthly rebates.
With monthly rebates, the cumulative total is calculated from the start of the calendar month until the start of the calculation period. The transactions in the calculation period are then put into brackets according to the cumulative total. If the calculation period spans multiple months. The cumulative total is reset to 0 at the start of each month.
In the rule setup, click the Amounts Per dropdown list and select Month.
For example, suppose the rule setup uses the Percentage of Value calculation method, the Value bracket basis, and there are three brackets. The results of the calculation depend on whether a cumulative total applies to the calculation period.
No cumulative total: If the calculation period is from June 1st to July 31st (two full months), the results are split into two month periods. As the calculation started at the start of the calendar month, there's no cumulative total to factor in, so the rebate for each month is calculated as usual, based on the brackets that are hit in that period.
Cumulative total: If the calculation period is from June 21st to July 31st (partial period), there is a cumulative total to factor in. In this example, the cumulative total from June 1st to 21st is 21,322. So, the partial period from June 22nd until the end of June is already in the 5% bracket.
