The Council must consult the Court of Auditors for its opinion prior to the adoption of certain Community regulations of a financial nature. Since the Amsterdam reform, the opinion of the Court of Auditors must also be sought before adopting any legislation to do with the combating and prevention of fraud. Furthermore, the Court of Auditors may give optional opinions on the request of one of the other institutions of the Community.

Opinion No 8/99 of the Court of Auditors, of 7 October 1999, on a Council proposal for a decision concerning the European Union's system of own resources. Submitted pursuant to Article 248(4) second subparagraph of the EC Treaty, it is therefore the result of optional consultation.

Opinion No 1/2000 of the Court of Auditors of 5 October 2000 on a proposal for a Council Regulation amending the Financial Regulation of 21 December 1977 and separating the internal audit function from the ex ante financial control function (fifth paragraph of Article 24 of the Financial Regulation). Presented pursuant to Article 279 of the EC Treaty, it is therefore the result of mandatory consultation.