The review of accounts for collectability and determination of the adequacy of the allowance for doubtful accounts is done in support of the "existence" assertion. In the context of auditing, the existence assertion refers to the belief that the accounts receivable and other assets exist in the company's records and that they are included in the balance sheet. The auditor must assess the risk of uncollectible accounts and determine the necessary adjustments to ensure that the allowance for doubtful accounts is reasonable and accurate. This process supports the assertion that the accounts receivable are real and exist as assets on the balance sheet