How to Understand EdpDiscount's Role with RIFee & RiVolumeDiscount in AWS CUR

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If you’re working on building cost analysis tools with data from the AWS Cost and Usage Report (CUR), you might find it confusing to figure out which charges are eligible for the Enterprise Discount Program (EDP) discount. Here’s a simple approach to understanding this better and determining the right way to calculate the base amount for EDP discounts.

First, identify the line item types included in your data. Common ones are Usage, RIFee (Reserved Instance fees), Fee, SavingsPlanCoveredUsage, SavingsPlanRecurringFee, SavingsPlanNegation, RiVolumeDiscount, EdpDiscount, BundledDiscount, SppDiscount, Credit, and sometimes FlatRateSubscription.

To rebuild the total charges for each line, you typically sum up the Usage, RIFee, SavingsPlanCoveredUsage, SavingsPlanRecurringFee, and possibly other discounts or fees. However, the tricky part is understanding what counts as the base amount for applying the EDP discount.

There are two main options to consider:

Option A: Include RIFee charges in the EDP calculation but subtract RiVolumeDiscount because that represents volume rebates that effectively reduce the total cost. So, the equation becomes:
EDP_eligible = Usage + RIFee – RiVolumeDiscount + Fee + SavingsPlanRecurringFee + FlatRateSubscription.

Option B: Exclude RIFee entirely from the EDP base, including only Usage, Fee, SavingsPlanRecurringFee, and FlatRateSubscription.

From analyzing similar data, Option A tends to be correct. It suggests that RIFee charges are eligible for EDP discounts, but volume rebates (RiVolumeDiscount) are rebates applied after the initial charges. Therefore, the discount from EDP applies only to the amount remaining after volume rebates are subtracted.

To confirm this, ask these questions:

Are RIFee charges considered eligible for the EDP discount?
Is RiVolumeDiscount applied before computing the EDP discount so that it reduces the base?
Are there other line item types, like Fee or SavingsPlanRecurringFee, that should be included in the EDP base?

If you or anyone else has analyzed CUR data and can clarify how these elements interact, your insights will be very helpful. Understanding these relationships helps ensure that your cost calculations are accurate and reflect how AWS discounts are actually applied.