Circular 230
Circular 230 is the set of Treasury rules that governs practice before the IRS. It applies to CPAs, attorneys, enrolled agents and others who represent taxpayers.
It sets duties such as due diligence, prompt return of client records, conflict of interest rules and the standards for written tax advice. The IRS Office of Professional Responsibility enforces it with reprimands, suspensions, disbarment and monetary penalties.
Example. A practitioner who learns a client omitted income on a past return must tell the client promptly about the error and its consequences, as Circular 230 §10.21 requires.
By Binod Raj Singh, CPA (licensed in Montana) · Updated for the 2026-2027 exam windows · Last updated 2026-11-05