Which assertion is important for both presentation and disclosure in auditing?

Completeness is a critical assertion for both presentation and disclosure in auditing because it ensures that all necessary information is included in the financial statements and related disclosures. In the context of auditing, completeness implies that all transactions, events, and circumstances that should be reported are indeed reflected in the financial statements. This assertion is essential to provide viewers of the financial reports with a full picture of the entity’s financial position and performance, as well as to ensure compliance with applicable accounting standards.

When it comes to presentation and disclosure, completeness specifically addresses whether the financial statements provide an accurate picture of the entity's financial activity and condition by including all relevant details. This assertion helps prevent omissions that could mislead users, such as investors or creditors, regarding the entity's overall financial health.

While the other assertions—accuracy, existence, and valuation—are also important in different contexts, they play a more specific role in other aspects of the audit process. Accuracy focuses on the correctness of the amounts recorded, existence verifies whether assets and liabilities actually exist, and valuation ensures that assets and liabilities are reported at the appropriate amounts. Completeness, however, encompasses the overarching necessity that all relevant information has been presented and disclosed properly, making it vital for the integrity of financial reporting.