What is the term for the starting date of a position?

The term "commencement date" specifically refers to the starting date of a position within employment contexts. This term is commonly used in contracts and legal documents to signal the official beginning of an employee's duties and responsibilities. It establishes the timeframe within which the employee is expected to start working and can be crucial for determining various rights and obligations, such as benefits eligibility and performance evaluations.

The other options, while they may seem plausible, are not standard terms used to denote the starting date in a formal employment context. For instance, "initial start date," "opening date," and "begin date" lack the legal specificity and recognition that "commencement date" carries, which is essential for clarity in employment contracts and agreements. Therefore, "commencement date" is the appropriate choice when identifying the officially recognized start of a position.