Which document is essential for tracking customer payments over time?

The statement is essential for tracking customer payments over time because it provides a comprehensive overview of all transactions related to a customer's account, including invoices issued, payments received, and outstanding balances. This document typically summarizes the account activity over a specific period, allowing businesses to easily monitor outstanding amounts and identify patterns in customer payment behavior.

In contrast, invoice history mainly focuses on details of each individual invoice rather than the total financial picture over time. The account ledger provides a more granular view of all accounts receivable transactions but may lack the organized summary format that a statement offers. A payment summary, while useful for consolidating payment data, would not provide the complete picture of both payments and outstanding invoices like a statement does. Therefore, the statement is the most effective tool for tracking how customer payments evolve over a defined period.