Original paper or electronic evidence of a transaction that supports bookkeeping entries, audit trails, and accounting review.
A source document is the original paper or electronic record that evidences a transaction or accounting event. It provides the facts that support bookkeeping entries, such as the date, amount, parties involved, and nature of the transaction.
Without source documents, recorded transactions are much harder to verify. Source documents support accurate journal entries, strengthen internal control, and form the evidence chain behind audit trails, reconciliations, and financial reporting.
Bookkeepers and accountants use source documents to prepare or validate entries before posting them into the accounting system. Different transactions rely on different documents, but the principle is the same: the record in the books should be traceable back to underlying evidence.
| Transaction Type | Common Source Document |
|---|---|
| Sale | Sales invoice, receipt, contract, shipping support |
| Purchase | Vendor invoice, purchase order, receiving report |
| Payroll | Timesheet, payroll register, approval record |
| Cash receipt | Receipt, remittance advice, bank support |
| Cash payment | Check support, EFT notice, approved voucher |
A business receives a vendor invoice for 1,200 of office supplies. Before recording the payable, the accountant checks the invoice, the purchase approval, and the evidence that the goods were received.
| Source Evidence | What It Confirms |
|---|---|
| Vendor invoice | Amount billed and supplier identity |
| Purchase approval | Spending was authorized |
| Receiving support | Goods or services were actually received |
Once those documents are in order, the accountant can post the related journal entry with stronger confidence.
A source document is not the same as the journal entry created from it. The source document is the evidence; the journal entry is the accounting record built from that evidence. It is also broader than paper invoices alone, because source documents can be digital approvals, bank records, contracts, or system-generated support files.