Will the Billing of a Reserved Instance (RI) Change If Commercial Discounts Are Changed or Added After the RI Is Purchased?

No. RI billing follows the rules below:

• If no discounts were applied during payment, the RI order will not be discounted even if a commercial discount is added later.
• If a discount was applied during payment, the RI order will continue to be billed at that discount within the remaining validity period, even if the commercial contract expires before the RI term ends.