# Window to add to or modify an existing invoice

You can modify an invoice after the invoice has been created and is still in [draft status](https://stripe.com/docs/invoicing/integration/workflow-transitions). A newly-generated invoice remains in draft status for [an hour after it has been created](https://stripe.com/docs/billing/invoices/subscription#adding-draft-invoice-items).
The best way to monitor the creation and status of an invoice is to set up [webhooks](https://stripe.com/docs/webhooks) to listen for [invoice.created](https://stripe.com/docs/api/events/types#event_types-invoice.created) and [invoice.updated](https://stripe.com/docs/api/events/types#event_types-invoice.updated) events respectively.
Invoices that are no longer in draft status and have been finalized can no longer be changed.
When an invoice is out of draft status, any new invoice items that are created will be applied to the next invoice.
## Additional Information
* If you are looking to add a one-time item to a customer’s first invoice, such as a setup fee, see: [Add a One-Time Fee or Discount With a New Subscription Plan](/questions/subscription-setup-fees).