Bookkeeping › Sales & Purchase Ledgers
Why are the sales and purchases ledgers called memorandum (subsidiary) ledgers?
BeginnerAnswer
They are memorandum because they hold the detail of individual customer/supplier balances but are not themselves part of the double-entry system—the double entry is captured in the control accounts in the nominal ledger. The subsidiary ledgers provide the who-owes-what breakdown supporting the single control-account total.
Real-world example The sales ledger lists each debtor, but the double entry sits in the receivables control account.