For example, the following is from an employment agreement dated January 2004 and refers, presumably, to the date the employee will actually start work: The term of this Agreement shall commence on the first day of the Company’s fiscal year commencing in the year 2004 (the “Effective Date”) and shall terminate on the last day of the Company’s fiscal year ending in the year 2007, subject to prior termination as set forth in Section 7 below (the “Term”).
Legally speaking, this is something that you should not do – or more accurately, there will only ever rarely be occasions when this is appropriate to do.
However in practice, for both good reasons and bad, backdating of documents does occur.
Instead, it’s the company’s obligation to pay the employee, and the employee’s obligation to work for that pay, that commences later, and that’s what I’d say in the contract.
If you need a defined term to refer to that later day, I’d use something like used in a contract to refer to some date in the past.
Lawyers who were trained in commonwealth jurisdictions may have an ingrained concept that backdating a document is generally improper, if not illegal.