Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
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You cannot directly downgrade from Microsoft 365 Personal to Microsoft 365 Basic because they are completely different plans and offer different benefits.
The Microsoft 365 Basic plan does not include premium desktop Office licenses. It only provides 100 GB of OneDrive (cloud) storage and 100 GB of Outlook email storage. So, you will have to cancel the Office 365 Personal Subscription here first -
Cancel your Microsoft subscription
Once canceled, you will receive the refund within 3-5 working days to your Original payment method.
You can then buy the Office 365 Basic subscription with the same Microsoft account.