Final answer:
Extending the fiscal year to include next year's sales violates the standard of ethical conduct related to competence, requiring truthful and accurate financial reporting.
Step-by-step explanation:
Extending the close of the fiscal year beyond December 31 so that some sales of next year are included in the current year would be a violation of the standard of ethical conduct for management accountants related to competence. This standard requires management accountants to provide accurate, clear, and concise information that is not misleading.
Deliberately manipulating the fiscal year to misrepresent financial results compromises the integrity of the financial reports. Such actions are in direct conflict with the ethical principles of competence, which emphasizes factual presentation of information and adherence to relevant laws, regulations, and technical standards.