Glossary
Invoice
Also called: bill · sales invoice
An invoice is a commercial document a seller sends to a buyer that itemizes goods or services delivered, states the amount owed, and sets the payment terms and due date. It creates the receivable in the seller's books and is the record both sides reconcile against.
Last updated October 13, 2026
Fields a professional invoice needs
The word 'Invoice', a unique sequential number, the issue date and due date, the seller's and buyer's names and addresses, a description of each line with quantity and unit price, subtotal, any tax with its rate, discounts, the total, the currency, accepted payment methods, and any tax or registration number your jurisdiction requires. For hourly work, each line should show hours and the rate.
Numbering and immutability
Invoice numbers must be unique and should be sequential without gaps, because tax authorities and auditors use them to prove nothing was hidden. Once an invoice is sent it should not be edited; corrections are made with a credit note or a replacement invoice that references the original. Billing software enforces this by freezing the invoice as a snapshot at the moment it is issued.
From invoice to payment
An invoice is paid when the buyer transfers the amount by the agreed method. Including a direct online payment link, clear bank details, and the due date on the document itself shortens the time to payment. Overdue invoices are followed up with reminders and, if the terms allow, late fees.
In Hoursmith
Hoursmith invoices are built from tracked time, fixed-fee allocations, expenses, and custom lines, numbered automatically, and frozen as an immutable snapshot when sent. Clients can pay online through your own Stripe account on Studio and above.