The most likely cause is that the subscription on the account is set up as a monthly recurring billing subscription at $19.99/month, not an annual subscription at $19.99/year. When recurring billing is on, Microsoft 365 subscriptions are billed automatically on the schedule configured for that subscription (monthly or annually). If the billing frequency was changed from annual to monthly, or if the subscription was originally created as a monthly plan, charges would appear every month.
To understand and resolve the overbilling:
- Check the subscription type and billing frequency
- Sign in to the Microsoft 365 account and go to Subscriptions at https://account.microsoft.com/services.
- Confirm whether the Microsoft 365 subscription is listed as a monthly commitment payment or an annual commitment payment.
- If it is a monthly commitment at $19.99, that explains the monthly charges.
- Review order history and charges
- Review the order history and banking/credit card statements over the last several months to confirm how often and how much has been charged.
- This will show whether the subscription has consistently been billed monthly and help document the overbilling concern.
- Adjust recurring billing if needed
- If recurring billing is on and the subscription should not renew monthly, turn off recurring billing or change the plan to the desired billing frequency. When recurring billing is on, the subscription continues to be billed on the day it was subscribed each period. Learn more at Manage recurring billing in the Microsoft 365 admin center (linked from the FAQ).
- Contact Microsoft Billing Support for correction/refund
- Because billing corrections and refunds require access to account-specific tools, contact Microsoft Billing Support so an agent can review the subscription, confirm the billing schedule, and determine refund options for the extra monthly charges.
- Use the support options described in the Microsoft 365 support articles (for example, Contact Microsoft 365 Support or Get support - Microsoft 365 admin). A billing agent can explain exactly why the charges occurred (e.g., monthly plan vs annual, change in billing frequency) and process any eligible refunds.
This behavior aligns with how Microsoft 365 subscriptions handle monthly vs annual commitment payments and recurring billing. If a subscription is on a monthly commitment or recurring billing is configured monthly, charges will appear every month until the billing settings or plan are changed.
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