The four documents side by side
| Document | Sent | Purpose | Asks for payment? |
|---|---|---|---|
| Quote or estimate | Before the sale | Offers a price, valid until a date | No |
| Proforma invoice | Before delivery | Previews a future invoice, e.g. for prepayment or customs | Sometimes, as a request for prepayment |
| Invoice | After or at the sale | Records the sale and the amount due | Yes |
| Receipt | After payment | Confirms the amount received and how | No |
When you need an invoice
Send an invoice whenever a customer pays after receiving goods or services, and whenever a business customer needs a document to account for the purchase. Where VAT or GST applies, the tax invoice is often the document your business customer needs to reclaim the tax, which is why tax authorities define its contents so precisely.
See what to include on an invoice for the details by country, or create an invoice now.
When you need a receipt
Give a receipt when a customer pays on the spot, pays in cash, or asks for proof of payment for an invoice. A receipt shows the date paid, the amount, the payment method and what it was for. In Singapore, for example, a GST-registered business should show its GST registration number on receipts as well as on tax invoices. [1]
The receipt generator adds the payment date and method and marks the document as paid. Use it only for payments you actually received; a receipt for a payment that never happened is a false document.
Keep both for your records
Invoices you send and receipts for what you pay are both supporting documents for your accounts. The IRS, for example, lists invoices and receipts among the records a business should keep to support its tax return. [2] Store the PDFs you download from BillCrisp with your other records; BillCrisp itself keeps documents only in this browser.
Can one document be both?
Yes, in practice: an invoice that shows it has been paid works as a receipt for many customers. In BillCrisp, press Paid in full to set Amount paid to the total; the invoice then shows a balance due of zero. Where a customer or tax office expects a separate receipt, issue one that refers to the invoice number.
Quotes and proforma invoices
A quote is an offer and creates no debt until it is accepted; make one with the quote maker. A proforma invoice looks like an invoice but is a preview, often used for prepayment or customs; it is not a tax invoice. See proforma invoice for the differences.
Sources
- [1] Inland Revenue Authority of Singapore (IRAS): Invoicing customers (accessed 2026-10-02)
- [2] Internal Revenue Service: What kind of records should I keep (accessed 2026-10-02)