Under Circular 230, a tax practitioner cannot charge a contingent fee for services before the IRS except in four narrow situations: defending an original return under IRS examination or challenge, filing an amended return or refund claim within 120 days of a written examination notice, pursuing a refund of assessed penalties or statutory interest, and representing a client in judicial proceedings under the Internal Revenue Code. Everything else — original return preparation, routine refund claims, tax planning, general advice — is off limits for results-based billing. The rule sits at 31 C.F.R. § 10.27, and violating it can lead to censure, suspension, or disbarment from practice before the IRS.1eCFR. 31 CFR 10.27 – Fees
What Counts as a Contingent Fee
A contingent fee is any fee tied, in whole or in part, to the outcome of a tax matter. The regulation names three common forms: a percentage of the refund, a percentage of taxes saved, or any fee that depends on a specific result being achieved.1eCFR. 31 CFR 10.27 – Fees
The definition also reaches money-back arrangements. If your engagement letter promises to refund part or all of the fee when a position gets challenged or doesn’t hold up — through an indemnity, a guarantee, rescission rights, or anything with similar effect — that is a contingent fee under the regulation.1eCFR. 31 CFR 10.27 – Fees The rule is written to catch the substance of the arrangement, not the label on it. Practitioners sometimes structure a “satisfaction guarantee” thinking they’ve stayed clear of Section 10.27 and find out otherwise.
The Default: No Contingent Fees for IRS Work
The baseline rule is a flat prohibition. A practitioner may not charge a contingent fee for services rendered in connection with any matter before the IRS.1eCFR. 31 CFR 10.27 – Fees That covers preparing original returns, filing refund claims outside the specific exceptions below, tax planning, written advice, and communications with the agency.
The policy reason is conflict of interest. When a preparer’s pay rises with the size of a refund, the incentive to inflate deductions or manufacture credits is obvious. Decoupling the fee from the tax result keeps the advice objective.
The Four Exceptions
Section 10.27 permits a contingent fee in these situations, and only these:1eCFR. 31 CFR 10.27 – Fees
- Services rendered in connection with an IRS examination of, or challenge to, an original tax return. Audit defense is the classic case, and a fee based on the reduction in proposed tax is allowed.
- An amended return or refund claim filed within 120 days of the taxpayer receiving a written notice of examination or challenge to the original return.
- A refund claim filed solely in connection with the determination of statutory interest or penalties assessed by the IRS.
- Any judicial proceeding under the Internal Revenue Code — including matters in the U.S. Tax Court, federal district court, or the Court of Federal Claims.
The exceptions share a pattern. Each one involves a contested matter: the IRS has already taken a position, or the dispute has moved into an adversarial posture. Circular 230 targets the preparation and advisory side of the practice; once litigation or a live dispute is on the table, contingent fees are back in play.
The 120-Day Amended Return Trap
The amended return exception is where practitioners most often stumble. A Form 1040-X or Form 843 filed on a contingent fee basis is permitted only when two conditions are both satisfied: the IRS has issued a written notice of examination or challenge to the original return, and the amended return goes in within 120 days of the taxpayer’s receipt of that notice.1eCFR. 31 CFR 10.27 – Fees
If a taxpayer walks in wanting to amend a return to claim a deduction they missed, and there’s no audit pending, a contingent fee is off the table. The IRS treats that as an extension of the original filing process. The position should have been on the original return, and charging a contingent fee to fix it raises the same conflict-of-interest concern as charging one for the return itself.
The 120-day clock runs from the taxpayer’s receipt of the notice, not the IRS’s mailing date. That gap can matter. Document the date of receipt, because filing on day 121 pushes the arrangement outside the exception.
One point of relief: a refund claim filed solely to recover assessed penalties or statutory interest sits under a separate exception and carries no 120-day limit.
Who Section 10.27 Reaches
Circular 230 governs everyone authorized to practice before the IRS — attorneys, CPAs, enrolled agents, enrolled actuaries, enrolled retirement plan agents, and registered tax return preparers.2eCFR. 31 CFR 10.3 – Who May Practice “Practice before the IRS” is defined broadly, covering preparing and filing documents, corresponding and communicating with the agency, giving written tax advice, and representing clients at conferences and hearings.3eCFR. 31 CFR 10.2 – Definitions The Treasury Department’s regulatory authority comes from 31 U.S.C. § 330.4Office of the Law Revision Counsel. 31 USC 330 – Practice of Representatives
What Happens if You Violate the Rule
Charging a prohibited contingent fee is a Circular 230 violation that can trigger disciplinary proceedings through the IRS Office of Professional Responsibility. Available sanctions are censure (a public reprimand), suspension from practice, and disbarment, which is a permanent ban.5eCFR. 31 CFR 10.50 – Sanctions
Sanctions under Section 10.52 require willful conduct.6eCFR. 31 CFR 10.52 – Violations Subject to Sanction Willful doesn’t mean malicious. Knowingly entering into a fee arrangement that meets the contingent fee definition without confirming an exception applies can be enough.
Treasury may also impose a monetary penalty, capped at the gross income the practitioner derived or expected to derive from the sanctionable conduct. A firm can face a separate monetary penalty if it knew or reasonably should have known about the violation. These monetary penalties can be imposed in addition to or in place of suspension or disbarment.4Office of the Law Revision Counsel. 31 USC 330 – Practice of Representatives
Before signing an engagement letter with any results-based component, run the arrangement against the four exceptions. If it doesn’t fit cleanly inside one of them, restructure the fee.