Additional Licenses during billing cycle

Add the two licenses in the Microsoft 365 admin center; they become assignable immediately, and Microsoft charges only for the portion of the current billing period during which those additional licenses are active.^1^

Add the licenses

1. Sign in to the Microsoft 365 admin center with the required billing permissions.
2. In Dashboard view, go to Billing > Your products. In Simplified view, select Subscriptions.
3. Select the relevant subscription, then select Buy licenses.
4. In Total licenses, enter the new total, not the number being added. For example, if you currently have 10 and need two more, enter 12.
5. Review the order and select Save.

For a Microsoft Customer Agreement (MCA), the account must have an appropriate billing-account or billing-profile owner/contributor role. For a Microsoft Online Subscription Agreement (MOSA), at least the Billing Administrator role is required.^1^

How the charges work

There are two components:

• Current partial period: A prorated charge for the two new licenses from the date you add them through the end of the current billing period.
• Next full period: Your normal recurring charge based on the new total license quantity.

Consequently, the next invoice can be higher than your future steady monthly amount because it may contain both the partial-period adjustment and the charge for the upcoming full billing period. Licenses added mid-period appear on the next invoice; annually billed subscriptions are invoiced within a month for the change.^1^

For example, if each license costs £12 per month and exactly half of the billing period remains:

• Prorated adjustment: 2 × £12 × 1/2 = £12
• Following full-period cost for those licenses: 2 × £12 = £24
• Possible additional amount attributable to the two licenses on the next invoice: £36, before taxes, discounts, or other adjustments

This is illustrative; the actual amount depends on your unit price, billing dates, taxes, discounts, billing frequency, and billing-account type.

Why the invoice may show credits and rebilling

If your account uses MOSA, the next invoice can show:

1. A credit reversing the previous charge for the original license count.
2. A prorated charge for the original quantity up to the change date.
3. A prorated charge for the new total quantity for the rest of that period.
4. The normal charge for the current license quantity.

This can look more complicated than a single charge for two licenses, but the invoice’s service periods and day counts show how the adjustment was calculated.^2^

The payment method associated with the subscription or billing profile is charged when the additional licenses are purchased, even though the adjustment is displayed on the next invoice.^1^

If Buy licenses is unavailable, check the subscription’s Purchase channel under Billing > Your products. A subscription marked Reseller must be changed through that reseller; one marked Prepaid requires another product key or a card payment method.^1^

References

1. Buy or remove licenses for a Microsoft business subscription
2. Understand your invoice for your Microsoft MOSA billing account