> For the complete documentation index, see [llms.txt](https://docs.bunny.com/guide/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.bunny.com/guide/tour/billing/proration.md).
# Proration
When an existing subscription is updated or a new subscription is added to an account that already has a subscription, proration typically comes into play as that those changes rarely fall exactly at the end of a billing period, which means that the change will be for a partial period.
For example, if an account has a subscription that runs from January 1 to December 31 and that subscription is changed April 1, the annual charges must be prorated remaining 9 months of the year.
Proration
Bunny will automatically suggest subscription end dates that are aligned with existing subscriptions, but you also have the option to choose a custom date.
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## 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, and the optional `goal` query parameter:
```
GET https://docs.bunny.com/guide/tour/billing/proration.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
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.