Audit report attachment requirement: returns must include the audit report or a prior-report copy with proof for compliance. The amendment replaces the phrase concerning an audit report obtained under the audit statute with wording that the return must be accompanied by the audit report referred to in the audit statute, or, where the report has been furnished prior to the return, by a copy of that report together with proof of its prior furnishing, and makes a corresponding substitution in the Explanation requiring either the audit report or a copy with proof of prior furnishing.