Upgrading from family plan to premium plan

If the upgrade is from Microsoft 365 Family to Microsoft 365 Premium, it is treated as an upgrade to a plan with more features, so the new plan can start immediately and the remaining value of the current subscription is converted into time on the new subscription.

For Family → Premium, Microsoft’s published conversion rate is 78%. That means the unused time on the Family subscription is not refunded as cash; instead, 78% of the remaining time is added to the Premium subscription.

What the reduced annual special means:

1. The promotional price applies to the Premium purchase price shown during checkout.
2. The remaining Family time is handled separately through the conversion rule.
3. The benefit is usually seen in the new renewal date on the subscription after the upgrade, not as a separate cash rebate.

Example:

• If 100 days remain on Family, upgrading to Premium adds about 78 days to the Premium subscription.
• The discounted annual offer lowers the price of the Premium plan purchase itself.
• These are two different things: promotional pricing and subscription-time conversion.

To verify exactly how it applied after purchase, sign in to the Services & subscriptions page and check the updated renewal date for the Premium subscription:

• https://account.microsoft.com/services

If switching to a plan with fewer features, Microsoft says that requires canceling the current subscription and buying another one. That does not apply here because Family → Premium is an upgrade.

References:

• Switch between Microsoft 365 subscriptions
• M365 premium upgrade from family. When is the prorata rate applied? - Microsoft Q&A
• Microsoft 365 Family subscription disappeared - Microsoft Q&A