What Is a Debit Note?

A debit note is a document that increases the amount a client owes after an invoice was issued. It quotes the original invoice number and shows the extra amount, so the original invoice stays unchanged and both sides can see why the balance went up.

Sellers issue one when the original invoice was too low: a missed line, a rate that was entered wrong, extra hours the client approved after the invoice went out, or a shipping cost added later. Buyers use the term too. In some industries a buyer sends a debit note to a supplier to formally request a credit, for example after returning faulty goods.

A debit note is the opposite of a credit note, which reduces what the client owes. Both carry their own numbering, such as DN-001 and CN-001, so neither clashes with your invoice sequence. If the change is large or the client hasn't approved it, a new invoice for the extra work is often clearer than a debit note.

Whichever you use, tell the client before it arrives. An unexpected increase is the fastest way to stall a payment.