Source Document

Source Document Definition

A source document is the original record that provides evidence a financial transaction occurred. These are the paper trail of your business — invoices, receipts, bank statements, contracts, purchase orders, and canceled checks. Source documents are the foundation of every bookkeeping entry and the backup you need if the IRS comes knocking.

Source Document in Practice — Example

A plumbing company completes a $1,500 job. The source documents for this transaction include: the signed service agreement (what was agreed), the materials receipt from the supply house ($340 in parts), the technician's time sheet (4 hours of labor), and the invoice sent to the customer ($1,500). Each document supports a different aspect of the transaction and together they create a complete, verifiable record.

Why Source Document Matters for Your Books

Source documents are the starting point for every journal entry. Without them, your books are based on guesses and memory — neither of which holds up during an audit. Every transaction in your accounting software should be traceable back to a source document.

For tax deductions, source documents are your proof. The IRS requires "adequate records" to substantiate deductions. A bank statement shows you spent $500 at Office Depot, but only the receipt proves what you bought and that it was a business expense.

Document retention is also a legal and practical requirement. The IRS recommends keeping most records for 3-7 years. Lost source documents can mean lost deductions, unresolvable discrepancies, or compliance violations.

How Source Document Shows Up in QuickBooks

In QuickBooks Online, you can attach source documents directly to transactions. When entering an expense, invoice, or journal entry, click the attachment icon and upload a photo or PDF of the receipt, invoice, or contract. QBO stores these digitally alongside the transaction. Use the receipt capture feature on the mobile app to photograph and auto-extract receipt data. This creates a digital source document library tied to your books.

Common Mistakes

Not keeping source documents at all — relying solely on bank and credit card statements leaves gaps in your documentation

Keeping documents but not organizing them — a shoebox of receipts is marginally better than nothing, but only if you can actually find what you need

Not attaching documents to transactions — QBO lets you link source documents to entries; use this feature so every transaction has its backup accessible in one click

FAQ

Q: What counts as a source document? A: Invoices, receipts, bank statements, canceled checks, contracts, purchase orders, shipping documents, time sheets, and any other original record of a transaction. Digital versions (photos, scans, PDFs) are accepted by the IRS.

Q: How long should I keep source documents? A: The IRS says 3 years from the filing date for most records, 7 years if you claim a loss from bad debt or worthless securities, and indefinitely for property records. When in doubt, keep it 7 years.

Related Terms

Receipt

Purchase Order

Reconciliation

Posting

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