Accounting firms got their first look last week at proposed new rules that would govern how accountants can serve their public company audit clients—no contingent fees, no tax shelters for audit clients, and no personal tax services for officers with financial oversight responsibility.

The Public Company Accounting Oversight Board issued its proposed ethics rules following months of debate and study, identifying those three circumstances as impairing an auditor’s independence. The board is accepting comments on the proposed rules before handing them up to the Securities and Exchange Commission for its review and approval.