A subledger is a ledger containing all of a detailed sub-set of transactions. The total of the transactions in the subledger roll up into the general ledger. For example, a subledger may contain all accounts receivable, or accounts payable, or fixed asset transactions. Depending on the type of subledger, it might contain information about transaction dates, descriptions, and amounts billed, paid, or received. A summary-level entry is periodically recorded in the general ledger. If someone is researching information in the general ledger in an account that contains this summarized level of information, he or she must then access the subledger to review transaction-specific information.
As part of their year-end tests, auditors may trace transactions from a subledger to the general ledger and from there to the financial statements, to ensure that transactions are being recorded properly in the accounting system.
In an accounting software package, a subledger is a database, rather than a manually-maintained book.
A subledger is also known as a subsidiary ledger.