Delegation Order 25-15, Authority of the Return Preparer Office to Perform Certain Tax Administration Functions Delegation Order 25-16 (Rev. 2), Authority of the Office of Professional Responsibility to Perform Certain Functions Concerning Practice before the Internal Revenue Service Delegation Order 25-17 (Rev. 1), Authority to Decide Protests of Enrollment or Re-enrollment Designation Denials Under Treasury Department Circular No. 230 Delegation Order 25-18 (Rev. 4), Authority to Authorize Students and Law Graduates at Low Income Taxpayer Clinics (LITCs) and Student Tax Clinic Programs (STCPs) to Practice before the Internal Revenue Service