(a) A person shall not undertake any engagement for the performance of professional accounting services or professional accounting work which he cannot reasonably expect to complete with due professional competence, including compliance, where applicable, with §501.60 of this chapter (relating to Auditing Standards), §501.61 of this chapter (relating to Accounting Principles), and §501.62 of this chapter (relating to Other Professional Standards).(1) Competence to perform professional accounting services or professional accounting work involves both the technical qualifications of the person and the person's staff and the ability to supervise and evaluate the quality of the work being performed.(2) If a person is unable to gain sufficient competence to perform professional accounting services or professional accounting work, the person shall suggest to the client the engagement of someone competent to perform the needed professional accounting or professional accounting work service, either independently or as an associate.(b) A person shall exercise due professional care in the performance of professional services.(c) A person shall adequately plan and supervise the performance of professional services.(d) A person shall obtain and maintain appropriate documentation to afford a reasonable basis for conclusions and recommendations in relation to any professional services performed.(e) Interpretive comment: The person may have the knowledge required to complete the professional services with competence prior to performance. In some cases, however, additional research or consultation with others may be necessary during the performance of the professional services.