Q.Why does vouching cash purchases carry a higher risk than vouching credit purchases?

Credit purchases leave a second, independent trail (the supplier's own ledger account) that cash purchases simply don't create.

In a credit purchase, a liability account for the supplier is created in the books, which remains open until payment is made — this gives the auditor an independent point of cross-verification (the supplier's own statement of account, or a direct confirmation request, can be compared against the business's own ledger balance for that supplier).

In a cash purchase, the transaction is settled immediately, and there is no continuing supplier ledger balance to cross-check against later. This means a dishonest employee could record an entirely FICTITIOUS cash purchase (with a fabricated or altered invoice), and — because there is no independent third-party record to contradict it — the fraud can be much harder to detect through vouching alone, unless the auditor specifically cross-checks the goods-received note, physica …

Students sometimes answer this in terms of 'cash is easier to steal than goods on credit' generally, without connecting the answer to the SPECIFIC audit-evidence point being teste …