Definition
A subsidiary ledger holds the detail behind one control account in the general ledger, such as each customer inside trade receivables or each supplier inside trade payables. The general ledger shows one total; the subsidiary ledger shows who or what makes it up. Its total must always equal the control account balance.
How it works
Without subsidiary ledgers, the general ledger would need an account for every customer, supplier and asset. Splitting the detail out keeps the chart of accounts short and the statements readable, while collections, payment runs and asset registers still work from individual balances.
In modern software the subsidiary ledger is usually not a separate book but a view: each line posted to receivables carries a party, and the party balance report is the subsidiary ledger. Because both views come from the same lines, they cannot drift apart.
When they do disagree, in spreadsheets or loosely integrated systems, the cause is nearly always a journal posted directly to the control account without a party, or a party-level adjustment that never reached the ledger. Reconcile the two every month.
Example: receivables control account and customer detail
Trade receivables in the general ledger show 18,400. The customer balances behind it add up to the same amount.
| Customer | Balance |
|---|---|
| Alpha Trading | 7,200 |
| Brightline Ltd | 5,950 |
| Cedar Studio | 5,250 |
| Total = control account | 18,400 |