Plain definition
A subsidiary ledger holds transaction-level detail for a particular class of balances, such as customer receivables, supplier payables, or inventory items. Its total is normally linked to a control account in the general ledger. The subsidiary ledger explains who or what makes up the total balance.
The subsidiary ledger answers “who makes up this balance?” A receivables control account of is not enough for collection; the customer ledger should identify the invoices, due dates, disputes, and customers that total it.
Illustrative example
Monetary examples use Saudi riyals (SAR). The same principles apply in other currencies.
Suppose the receivables control account is but individual customer balances total . The team traces the difference to a cash receipt credited to the control account but not applied to the customer’s account in the detailed ledger.
Applying that receipt to the right customer reduces the detailed total to . The team does not record the cash again. It corrects the missing customer allocation before using the ageing report to chase payment.
Why it matters
Detail supports collection, payment, and investigation; the control account provides an independent reconciliation point.
Practical consequence
At close, compare the total detailed ledger to the control account and investigate the difference by transaction. A single net adjustment hides whether the problem is an invoice, cash application, credit note, interface, or manual posting.