The parts of an invoice
- Seller details: business name, address, tax ID
- Buyer details: name and billing address
- Unique invoice number and issue date
- Due date (or payment terms like Net 30)
- Itemized lines: description, quantity, unit price
- Tax per line or on the subtotal
- Discounts, if any
- Total amount due
- Payment instructions
Invoice vs receipt vs bill
The invoice requests payment (seller → buyer, before money moves). The receipt confirms payment (often buyer-facing, after money moves). 'Bill' is simply the buyer's word for the invoice they received.
Why invoices matter
For the seller, an invoice starts the clock on receivables and is the primary sales record for tax. For the buyer, it is the evidence that authorizes payment. For both, it is the document auditors and tax authorities look for first.
When an invoice becomes binding
An invoice itself is not a contract — it records one. The binding terms live in the contract or order the invoice references; that is why good invoices carry a PO or quote number.
Frequently Asked Questions
Is an invoice a legal document?
It is a legally meaningful record — evidence of a transaction and often a tax document — but it derives its force from the underlying agreement between the parties.
Can an invoice be sent after payment?
Yes, some businesses issue a 'paid invoice' as the receipt itself; functionally it becomes the proof of purchase.
What makes an invoice invalid?
Common fatal flaws: missing tax ID when tax is charged, duplicate or missing numbers, and no issue date. Any of these can make a tax authority reject it as input tax evidence.
Do individuals ever issue invoices?
Sole traders and freelancers do constantly; private individuals only when selling something taxable in a business-like way — otherwise a receipt is enough.