What documentation must always accompany a GPC transaction?

The correct choice emphasizes the necessity of having a detailed invoice accompany a Government Purchase Card (GPC) transaction. A detailed invoice provides a comprehensive record of the items or services purchased, including quantities, descriptions, prices, and any applicable taxes or fees. This documentation is crucial for ensuring transparency, accountability, and compliance with financial regulations governing GPC transactions.

Without a detailed invoice, there is a lack of evidence to support the transaction, which could lead to difficulties in reconciling purchases, justifying expenses during audits, or verifying that the proper goods or services were received. The invoice also aids in establishing a clear financial trail, which is essential for tracking spending and ensuring that GPC usage adheres to the established guidelines and policies.

Other forms of documentation, such as a letter of justification, purchase agreement, or the vendor's contact information, may be necessary in specific circumstances, but they do not serve the primary function of providing a straightforward account of the transaction as the detailed invoice does. Hence, having the invoice is vital for every transaction to maintain the integrity and compliance of the purchasing process.