What kind of audit is usually the most comprehensive?

A field audit is typically the most comprehensive type of audit conducted by tax authorities. During a field audit, the auditor goes directly to the taxpayer's location, which allows for a thorough examination of the books, records, and supporting documents that pertain to the taxpayer's financial activities. This face-to-face interaction enables the auditor to ask questions, clarify details, and assess the taxpayer's operations in the context in which they conduct their business.

Field audits often review multiple aspects of the taxpayer's financial situation, including income, expenses, deductions, and compliance with tax laws. This direct engagement helps ensure that all relevant information is available and considered, leading to a more accurate and informed evaluation of the taxpayer's tax obligations.

In contrast, an office audit usually takes place at the tax agency's office and focuses on specific issues or discrepancies, while a correspondence audit is conducted primarily through mailed requests for information. Document reviews are limited to the analysis of the submitted documents without additional dialogue or in-depth investigation, making them less comprehensive than field audits.