Is it possible to move an Azure MCA subscription to a CSP

Yes, you can do that by doing a billing change. It's described here. https://docs.microsoft.com/en-us/azure/cost-management-billing/manage/transfer-subscriptions-subscribers-csp#transfer-ea-subscriptions-to-a-csp-partner Basically, for the matrix, you can do a EA (MCA/SCE) to CSP and from PAYG to EA. You will keep your subscription ID in the process, and with no downtime for the users. The process from EA to CSP has to be initated from your CSP partner. All other migrations are ressource by ressource migrations

it is important to understand that moving a subscription to CSP requires that you create a new Azure subscription under the CSP program. This means that you will have two separate subscriptions: the original MCA subscription and the new CSP subscription. The resources in the MCA subscription will not be automatically moved to the new CSP subscription, and you will need to manually move them if you want to do so.