Check, cash register slip, deposit slip, invoice, voucher, etc., that evidences a business dealing. Source documents are a critical part of an audit trail for establishing the authenticity, and tracing the history, of a transaction.
Use 'source document' in a Sentence
The source document which was needed to verify the actual sale could not be located by all parties involved, delaying the sale.
The source document was in my hand, so I had proof that we had made the transaction and we were going to be okay.
You need to make sure you have good records of any source document so that you know everything really got done corretly.