It depends on whether that person is an independent contractor or employee. If the person is an employee and creates the work within the course of his or her duties for you as the employer, then you do not need a separate written agreement. Just the fact that the person is an employee and you’re the employer is enough to grant you the copyright to the work (as long as the work is created in the course of employment for the employer).

If the person is an independent contractor, then you must have a written agreement granting you copyright ownership to the work. You’ll want to create a separate agreement or clause within the independent contractor agreement granting you, i.e. the employer, the exclusive rights to the works created by the independent contactor.

Keep in mind that the written agreement is a contract and must meet the 3 general principals of a contract, including (i) an offer, (ii) acceptance, and (iii) consideration (e.g. generally money). Also, the written agreement should be signed before any work is started. If you attempt to sign the agreement after work is begun, you may have to create an assignment agreement to own the work instead of a "work made for hire" agreement.

The author and owner of the work is the employer. An employer can be an individual, corporation, or other entity. The employer therefore holds the copyright to the work. The actual individual or individuals who created the work are not considered the authors or owners of the work under copyright law. However, the employer can always grant back certain rights or all the rights to the copyrighted work to the individuals that created the work.

This question actually went all the way to the United States Supreme Court in the 1989 case Community for Creative Non-Violence v. Reid, 490 U.S. 730. The Court talked about how to determine if an individual is an "employee" or "independent contractor" for "work made for hire" purposes.

In short, the Court listed a number of factors to take into consideration in determining if an individual is an "employee" or "independent contractor." One of the key considerations is how much "control" an employer has over the individual and his or her work. The more control an employer has over an individual the more likely that individual is an employee, and not an independent contractor. However, there are many other factors to consider with no 1 factor as determinative. We recommend that you read "Work Made for Hire" for further details on this question and/or the US Supreme Court’s decision cited in this response.

Next, we’ll go over work made for hire questions 4 through 6.