Answer
Rule 203 is a rule of the Code of Professional Conduct that prohibits a member of the AICPA from expressing an unqualified opinion on financial statements that largely contain material departure from GAAP. AICPA members are usually required to prepare financial statements that are in accordance with GAAP.
Work Step by Step
Additionally, failure to follow rule 203 can lead to a loss of CPA's licence to practice and for that its apparent that its an extremely vital rule which requires auditors to follow the FASB standards keenly.