A CPA is a certified public accountant, and is engaged in a number of advisory roles for his or her clients. These roles include the tasks noted below. Of the following activities, the only one that a CPA is specifically certified to do is the audit. All of the other items can be provided by other parties who are not certified public accountants. However, the CPA designation implies a high level of training and expertise, since he or she is required to take a certain amount of continuing professional education on an ongoing basis and must periodically pass an ethics examination. These requirements may attract clients even when there are non-CPA competitors who are willing to provide the same services.

There are limitations on the ability of a CPA to provide services other than audit work to a client, in order to avoid giving the appearance of being too closely associated with the client. The choice may be to only provide audit services, or to provide everything but audit services.

The main activities of a CPA are as follows:

Audits and reviews. The primary task of the CPA is to audit the books of clients. If the resulting financial statements of a client meet the CPA's evaluation criteria, the CPA will issue an auditor's opinion concerning the financial statements that accompany the statements when they are issued to third parties. A lesser form of an audit is a review, which clients may prefer due to its lower cost.
Consulting services. Clients may ask a CPA to engage in a number of consulting activities, such as advising on the adequacy of a system of controls, describing possible strategic options, or assisting in the installation of information systems.
Taxation services. A major service area for the CPA is to advise on the tax strategies of clients, as well as to prepare their tax returns. Many CPAs specialize in this area, and perform no other services.
Forensic accounting. Some CPAs specialize in forensic accounting services, where they reconstruct destroyed financial records or investigate whether fraudulent activities have occurred. In some cases, they are expected to testify in court as to their findings.
Financial planning. A CPA may advise a client with financial planning advice, such as how to transfer a business to a buyer with the minimum amount of short-term tax impact on the client. This area can expand to estate planning, so that clients can bequeath assets at the minimum tax cost to recipients.
Litigation services. A CPA can provide much of the detailed analysis required by an attorney to present a winning case in court. These skills are needed for divorce settlements, disputes between businesses, bankruptcy proceedings, and so forth. An experienced CPA may provide testimony as an expert witness.