The Circular 230 conflict of interest rules, set out in 31 C.F.R. § 10.29, allow a tax practitioner to represent clients with competing interests only if the practitioner reasonably believes each client can still receive competent and diligent representation, no other law prohibits the work, and every affected client gives informed consent confirmed in writing within 30 days. The Treasury Department enforces these requirements through the Office of Professional Responsibility, and the penalties reach censure, suspension, disbarment, and monetary fines equal to everything the practitioner earned on the engagement.
What the Rule Counts as a Conflict
Two distinct situations trigger the rule. The first is direct adversity: representing one client whose position is directly adverse to another client’s. Preparing returns for both the buyer and the seller in a business acquisition is the textbook case, because a purchase-price allocation that helps one side almost always hurts the other.
The second is broader and easier to miss. A conflict also exists when there is a significant risk that your representation of a client will be limited by your responsibilities to another client, a former client, a third party, or your own personal interests. No one has to be on opposite sides of a dispute. A financial stake in the transaction you are advising on, a family tie to someone involved, or the prospect of future employment with a party can all compromise your judgment enough to count.
How Conflicts Show Up in Tax Practice
Some are obvious. Representing both spouses in a divorce is one. Others are quieter and cause more trouble because practitioners walk into them without noticing.
Preparing the S corporation return along with both shareholders’ individual returns looks routine until one shareholder asks for structuring advice on buying the other out. At that moment you are helping one client negotiate against another. The same pattern appears when you advise both the vendor and the purchaser on a single transaction, when tax planning for a company’s executives runs against the company’s own interests, or when multiple family members share an estate or gift plan whose tax outcomes pull in different directions. The common thread is that undivided advice to each client becomes impossible once their financial interests diverge.
When You Can Keep the Engagement
A conflict does not automatically end the representation. Section 10.29 lets you continue if you clear two thresholds and then document the client’s agreement.
First, you must reasonably believe you can provide competent and diligent representation to each affected client. Hope is not the standard; the belief has to be one a careful practitioner in your position would share. Competence is its own obligation under the regulations, requiring appropriate knowledge, skill, and preparation, and it becomes more demanding in a conflicted matter because you owe full-quality work to more than one client whose interests compete.
Second, the representation must not be prohibited by any other law. Federal ethics statutes, state bar rules, and CPA licensing requirements can each independently bar an engagement that Circular 230 would otherwise permit. If either threshold fails, you decline the new engagement or withdraw from the existing one.
Informed Consent, in Writing, Within 30 Days
Once you decide to proceed, every affected client must waive the conflict after receiving informed consent. “Informed” is doing real work in that phrase. You have to explain what the conflict actually is, how it could affect each client’s position, and what the risks of shared representation are. Telling a client that “other clients exist” does not meet the standard.
Written confirmation follows. The consent itself has to happen when the conflict becomes known to you, but the written documentation can come within a reasonable period, capped at 30 days. Blowing past that 30-day window is a regulatory violation even if the client verbally agreed weeks earlier.
Electronic signatures can satisfy the writing requirement. Under the E-SIGN Act, electronic records and signatures are generally valid for transactions affecting interstate commerce, provided the client has affirmatively consented to receiving records electronically. Before that consent counts, the client must be told they can request a paper copy and withdraw electronic consent, and they must have the hardware and software to access the record. A recorded verbal agreement is not an electronic record.
Keeping the Waiver on File
Signed consents are not documents you file and forget. Section 10.29(c) requires practitioners to retain copies of all written consents for at least 36 months after the representation ends. Any IRS officer or employee can request to inspect those records during the retention period.
Three years is longer than it sounds. The clock does not start until the representation actually concludes, and tax matters routinely stretch across multiple years of audits and appeals. A practitioner handling a multiyear audit that closes in 2028 has to keep the waiver until at least 2031. A reliable retrieval system is part of complying with the rule, not a nicety on top of it.
Extra Rules if You Used to Work for the IRS or Treasury
Practitioners who previously worked for the IRS or the Treasury Department face a separate layer of conflict rules under 31 C.F.R. § 10.25, which incorporates the criminal restrictions of 18 U.S.C. § 207. These exist because a former government employee carries inside knowledge of specific cases and specific decisions.
The restrictions run on a tiered schedule:
- If you personally and substantially participated in a specific matter involving specific parties while in government, you can never represent or assist any party in that same matter after leaving.
- If a matter involving specific parties fell under your official responsibility within your last year of government employment, you cannot represent anyone in that matter for two years after you leave.
- If you participated in developing a rule or regulation, you cannot contact any Treasury employee about that rule’s publication, amendment, or interpretation for one year after leaving. You can still represent a taxpayer in a dispute about how the rule applies to their situation, as long as you do not use confidential information from the rulemaking process.
The line between “personal and substantial participation” and “official responsibility” carries a lot of weight. A revenue agent who spent months building a case against a taxpayer is permanently barred from switching sides on that case. A supervisor whose name appeared on the file because it fell within their division, but who never touched the substance, faces the two-year restriction instead.
What Happens if You Get It Wrong
The Office of Professional Responsibility has a graduated set of sanctions. Censure is a public reprimand; censured practitioners are named in the Internal Revenue Bulletin, so the sanction is visible to other tax professionals and to clients who look. There is no private-reprimand option in the regulation. Suspension bars practice before the IRS for a set period. Disbarment is the most severe sanction, and while it is not necessarily permanent, a disbarred practitioner cannot even petition for reinstatement until five years have passed, and the IRS will only grant it if convinced the conduct will not repeat and reinstatement would not harm the public interest.
On top of any practice restriction, the Secretary of the Treasury can impose a monetary penalty. The cap is the total gross income the practitioner earned, or expected to earn, from the conduct that triggered the sanction. If the practitioner was acting on behalf of a firm, and the firm knew or should have known about the misconduct, the firm can also be penalized. A monetary penalty can be imposed instead of or in addition to censure, suspension, or disbarment.
For most practitioners, the formal sanction is only part of the cost. Legal fees during a contested proceeding, clients lost while the case runs, and the reputational effect of a published disciplinary action generally outweigh the sanction itself. That math is what makes the front-end work, honest analysis of the conflict, careful disclosure, a signed waiver within 30 days, and a retention system that can produce it three years later, worth doing carefully the first time.