Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Hello !The AI answer above is partly correct.
When you upgrade from a Microsoft 365 Personal subscription to a Family plan, you do pay the full Family price upfront. Your remaining time on the Personal plan is not refunded as cash and you do not get a prorated refund.
However, your unused Personal time is converted into additional time on the new Family subscription. The conversion table is available here : https://support.microsoft.com/en-us/office/switch-between-microsoft-365-subscriptions-3fcc1efc-2722-427f-8efa-db94b9b0a36b
Hence, after the conversion, your Family subscription end date will reflect the paid year + the converted remaining Personal time.
Please let me know if you have any other question !