# Billing day Every account has a billing day that determines which day of the month invoices are generated. This day is set the first time the first time an account subscribes to a product and it will be the billing day for the lifetime of the account. The billing day also plays an important role in proration of charges, i.e. when subscriptions are changed mid-cycle. When additional subscriptions are added to an account, they will all be co-termed with the first subscription that was created. ### Forcing the billing day When creating subscriptions via Bunny's API, you can specify a billing day that is different from the current date. For example, you can use this if you want all customers be billed on the first day of the month so their invoices are aligned with calendar months. ### Billing day reset For an account with active subscriptions, the billing day will stay constant. However, when an account ha no active subscriptions and a *new* subscription is created, the billing day will be reset to the start date of that subscription. This ensures that the subscription period will not be prorated, which will be more intuitive in that situation. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.bunny.com/guide/tour/billing/billing-day.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.