Are contingent fees always prohibited for every tax matter?

No. The exam answer depends on the service and the applicable professional rule. Contingent fees are especially problematic for original return preparation and routine refund claims. Some contested or examined matters may have narrower exceptions, but the CPA must verify the rule, document the scope, and consider state board and independence requirements.

The important habit is not memorizing "always" or "never." The habit is classifying the engagement:

• original return preparation;
• amended return or refund claim;
• IRS examination or formal dispute;
• attest-client service.

Each category can change the ethics analysis.