Read the account activity
Use the customer/supplier account to see source documents, settlements and the remaining balance. The subledger should explain the corresponding debtor or creditor control balance.
Opening balances
When migrating a client, bring forward customer and supplier detail where it matters. An opening subledger balance can later be matched to the bank even if no invoice exists in Balansix for the historic item.
Allocate receipts and payments
Use settlement matching for partial payments, one receipt against several invoices, several receipts against one invoice and on-account amounts. Do not create a new invoice merely to make the bank line disappear.
Reconcile the control account
At period end, the customer/supplier subledger total should agree to the related Trial Balance control account. Investigate differences through opening balances, source documents and settlement allocations before finalisation.