I'd be glad to help you in marking your invoice as paid without having to send it to your customer's email address, Image plus.
If you already have an invoice created in QuickBooks Self-Employed (QBSE), you can edit it first and then mark it as paid after editing your customer's information.
Please follow these simple steps:
- Log in to your QuickBooks Self Employed account.
- Navigate to the "Invoices" section from the left-hand menu.
- Find the invoice you want to edit and click on it to open the invoice details.
- Click the "Edit" button located at the top right corner of the invoice page.
- Make the necessary changes to the invoice, such as editing the customer details, adjusting the invoice items, updating quantities or prices, or modifying payment terms.
- Once you've made the changes, Click the "Save" button to save the changes you made to the invoice.
- You can either Subscribe to send or hit the dropdown button and choose Save.
- Click the dropdown button and find the Mark as paid button.

You can also create and customize your invoice in QBSE so it will enhance the appearance and professionalism.
Additionally, learn how to export and get reports in QuickBooks Self Employed to monitor your daily income and expense.
Should you require any additional assistance regarding how to mark an invoice as paid, please do not hesitate to reach out to us. We are here to provide support and ensure your experience is seamless. Have a great day ahead.