Attest Service: What it is, How it Works

Attest Service

Investopedia / Dennis Madamba

What Is an Attestation Service?

An attest service, or attestation service, is an independent review of a company's financial statement conducted by a certified public accountant (CPA). The CPA delivers an attestation report with conclusions about the reliability of the data.

The standards for attestation services are developed and published by a professional services group, the American Institute of Certified Public Accountants (AICPA). In recent years, the standards have been updated to reflect a wider range of attest services unrelated to financial reports. For instance, a company might request an attest service on its consumer privacy statement.

Understanding the Attest Service

In law, an attestation is a declaration by a witness that a legal document was properly signed in the presence of the witness. Essentially, it confirms that a document is valid. A notary public provides an attestation for documents.

In finance, an attestation service is a CPA's declaration that the numbers are accurate and reliable. As the service is completed by an independent party, it validates the financial information prepared by internal accountants.

There are three main types of attest functions including a comprehensive examination, a review of an examination completed by another party, and a partial examination that is limited to an analysis of specific procedures.

Key Takeaways

  • An attest function is a CPA's review of a company's financial statement.
  • After a comprehensive review, a CPA delivers an opinion on the integrity of the numbers in the statement.
  • A company may also seek a review or a partial examination.
  • A comprehensive examination concludes with the CPA expressing an opinion on the overall accuracy and integrity of a company's financial statement. This level of scrutiny is the equivalent of a financial audit.
  • A review is similar to a second opinion. It confirms the results of a previous audit or uncovers any issues that might have been missed.
  • A partial examination is limited to particular aspects of the company's bookkeeping processes.

All three attest functions must follow standards set by the AICPA with respect to audit procedure, independence, and expression of opinion.

CPAs increasingly are asked to perform attest services on non-financial documents such as security and privacy control statements.

The attestation review is one of the most important duties of a CPA. In 2011, Statement on Standards for Attestation Engagements (SSAE) No. 16 replaced Statements on Auditing Standards (SAS) No. 70 as the authoritative guide for CPAs performing audits.

This document, called AT Section 801 of SSAE No. 16, outlines the goals of an attest function. It also broadens the definition. According to AICPA, certified public accountants increasingly are being asked to perform attest services on non-financial procedures. These often are meant to prove compliance with complex government regulations and requirements. They might include reports on security procedures, privacy controls, and greenhouse gas emission reports, to cite a few examples.

Article Sources
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  1. SSAE 16. "SSAE 16 Overview." Accessed Feb. 10, 2021.

  2. American Institute of Certified Public Accountants. "AT Section 801, Reporting on Controls at a Service Organization." Accessed Feb. 10, 2021.

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