One sequence per business

Use a number you can say out loud. InvoiceMint suggests INV and the year, then a counter, such as INV-2026-0007. You can replace it, and the app will refuse a second saved invoice with the same number on your account.

Gaps are normal if you delete a draft. Uniqueness matters more than a perfect sequence.

Due dates are a promise you type

The issue date and the due date are calendar dates you choose. The due date cannot be earlier than the issue date. Nothing here calculates statutory interest or late fees. If your contract adds a late fee, add it as its own line when you decide to charge it.

When a sent invoice becomes overdue

If an invoice is marked Sent and the due date is before today, the dashboard shows it as Overdue. Paid, cancelled, and draft invoices are left alone. You can also set the status yourself.

Duplicating an invoice starts a new draft with a new number and a zero amount received. The original stays as it was.