Definition
An invoice is a commercial document issued by a seller to a buyer that itemises a transaction (goods or services supplied), the amount due, and the payment terms. It serves two purposes: as a request for payment and as a record of the underlying sale. An invoice is distinct from a receipt (which confirms payment received), a proforma invoice (which is a quote-stage document with no payment obligation), and a tax invoice (which adds the fields required to support input tax recovery by the customer).
What an invoice means in practice
For a bookkeeper, every invoice issued is the start of an accounts receivable lifecycle. The invoice posts as a debit to AR and a credit to revenue (plus output VAT or GST if the supplier is registered). The customer pays, the bank reconciliation matches the deposit against the open invoice, AR clears, and cash increases.
The invoicing process in modern platforms is streamlined: Xero, QuickBooks, FreeAgent, and similar tools let a user create the invoice from a saved template, populate from a contact and item list, email the PDF, and track the payment status. Most platforms include a “view online” link in the emailed invoice so the customer can pay by card or bank transfer with one click. The integration between invoicing and the bank feed means payment reconciliation usually requires no manual intervention.
A practical example: a UK consultancy completes a 5,000 project for a client. They create an invoice in Xero on 1 November with Net 30 terms. The invoice automatically picks up the customer’s address from contacts, applies 20% VAT (1,000), and emails as a PDF with a pay-now link. AR increases by 6,000; revenue by 5,000; output VAT by 1,000. On 28 November the client pays via Stripe. The Stripe deposit reconciles against the open invoice in Xero, clearing AR back to its prior position and increasing the bank balance by 5,820 (after Stripe’s 3% fee of 180, which posts as a separate bank-charges expense).
How invoices work by country
United Kingdom
Non-VAT invoices need the supplier’s name and address, the customer’s name and address, a unique identification number, the invoice date, a description of the goods or services, and the total amount due (per GOV.UK “Invoicing and taking payment from customers”). Sole traders must include the trader’s name and any business name being used. Limited companies must show the full registered company name and either name no directors or name all of them; partial director lists are not permitted.
VAT-registered businesses must issue tax invoices for taxable supplies, which add the VAT registration number, VAT amount, and per-line VAT rates. The three HMRC tiers (simplified, modified, full) apply by amount.
Australia
Non-GST invoices (issued by suppliers below the AUD 75,000 GST threshold who have not voluntarily registered) must say “Invoice” (not “Tax Invoice”) and include a statement that no GST has been charged. The supplier’s name, the buyer’s name for amounts above AUD 1,000, the date, and a description are mandatory under the Australian Consumer Law. GST-registered businesses issue tax invoices instead, with the additional ABN and GST fields the ATO requires.
Canada
Non-GST invoices require the supplier name, invoice date, total amount, and customer name. The peculiarity in Canada is that any sale by a GST/HST-registered business must include the GST/HST number, which then qualifies the document as a tax invoice. So a non-tax invoice is only possible from a non-registered supplier, which limits the practical scope of the “plain invoice” category in CA.
New Zealand
Non-GST invoices (issued by non-registered suppliers) need the supplier’s name and address, the customer’s name, the date, and a description of the supply. The “tax invoice” label is now optional under the April 2023 GST reforms even for GST-registered suppliers, who instead issue “taxable supply information” with broadly similar content to the old tax invoice.
Singapore
Non-GST invoices include the supplier’s name and Unique Entity Number (UEN), the customer’s name, the date, a description, and the amount. GST-registered businesses must issue tax invoices with the additional fields specified in IRAS section 7.1.4. The UEN is mandatory on every invoice from a registered Singapore entity, GST-registered or not.
Related terms
The invoice sits at the centre of the sales cycle:
- A tax invoice carries the additional fields needed to support input tax recovery by the customer.
- A proforma invoice is a pre-sale quote document with no payment obligation or tax-recovery force.
- A sales invoice is a synonym for invoice in many contexts, particularly UK accounting software.
- The invoice creates the accounts receivable entry that tracks the customer’s outstanding balance.
- A credit note is the document that reverses an invoice or applies a discount after the fact.
See also
For the practical mechanics of recording invoices in Xero or QuickBooks, see the per-software workflow guides as they ship.
FAQ
See the answered questions above for invoice vs receipt, invoice vs tax invoice, and sequential numbering requirements.