I need to upgrade from Team to Business mid-month - will the upgrade be prorated?

Monthly charges for Business-plan upgrades are not prorated. The most cost-effective time to upgrade your plan is immediately after the monthly cycle has started.

Annual-plan charges are pro-rated in monthly segments. If you upgrade 6 months into an annual plan you will only be charged the difference for the remaining six months of the upgrade.

Warning: On-demand/pay-as-you-go events are charged based on the plan tier at the END of the monthly period. Business plan on-demand events are typically more expensive than Team plan on-demand events. You can view the per-category event pricing here: https://docs.sentry.io/product/accounts/pricing/#per-category-pricing