Back in October 2022 Microsoft announced that there would be changes to the exchange policy for Azure Reservations. That change has been postponed repeatedly until now.

At the end of July 2026 there was an announcement that from 1 February, 2027 Reservations purchased for any service supported by one of the Azure Savings Plans would no longer be eligible to be exchanged. If you’ve got an existing Reservation then you can exchange it one more time after 1 February, 2027.

Find the announcement with some useful examples here: https://bit.ly/3RtHaVX.