If you were not an employee at the time you made the logo, then you retained the rights and they have a license. You should consult with an attorney before signing an assignment.

There are different kinds of intellectual property: copyright, trademark, and patents. The kind to which you refer here is copyright. Copyright is the intangible right to control how your artwork is reproduced, including how it is “used, altered or otherwise exploited” (17 U.S.C. Sec. 106).

Although the general rule in copyright law is that the person who creates a work (in this case, you) is the "author" of that work, there is an exception in the category of works called “works made for hire.” If a work is “made for hire,” the employer, and not the employee, is considered the author of the work.

Whether a particular work is made for hire is determined by the relationship between the parties. To determine whether a work is made for hire, you first must ascertain whether the work was prepared by (1) an employee or (2) an independent contractor.

If a work is created by an employee, generally the work is considered a work made for hire, and the company is the author. On the other hand, if the work is created by an independent contractor, then the work is a specially ordered or commissioned work, and can only be made for hire only if (1) there is a written agreement between the parties specifying that the work is a work made for hire and (2) the work must be specially ordered or commissioned for use as a contribution to a collective work, as a part of a motion picture or other audiovisual work, as a translation, as a supplementary work, as a compilation, as an instructional text, as a test, as answer material for a test, or as an atlas.

So, in a nutshell, if you were an employee, the company is the "author" of the work. However, if you're an independent contractor, you are the "author" unless you signed a written agreement specifying that the work was a work for hire for hire. It's not always easy to determine whether you were an employer or independent contractor. The courts look at various factors, which are: (a) control by the employer over the work, (b) control by employer over the employee, and (c) status and conduct of employer.

If the company is the author (meaning you were an employee when you did the work or you were an independent contractor with a written agreement and the work qualified), then it has all ownership rights in the work and you have nothing to transfer.

If, on the other hand, you are the author, you can transfer your rights in the work. If your contract doesn’t explicitly transfer the ownership of copyright, you will be granting the company a license to reproduce the logo under your copyright ownership. The scope of the license depends on the agreement between the parties or, if the agreement is silent, on what is reasonable under the circumstances.

Because a logo is intended to be a company identity and used by only that company, it is probably reasonable for the company to expect that, in entering into the agreement with you to do the logo, you gave it the exclusive right to reproduce the logo without limitation, and perhaps even to make “derivative works” of it.

As to whether you can "put a price" on the ownership of the copyright, it is true that copyrights can be bought and sold, and often are. However, you also should consider what was your intent when you entered into the agreement with the company to design the logo, and if such intent was established up front. Was it your intent to retain some of the rights of the logo? If you request more money now, and you are going against your original intent, you may be breaching your agreement.

Another thing you may want to consider, if you do sign a document signing over rights, is to add some sort of clause stating that you would retain nonexclusive, perpetual and worldwide right to display, reproduce, and distribute the logo in your own portfolio, which may include your own website as well as third-party trade publications or exhibits, solely to promote or provide an example of your own work, and that you also retain the right to be credited with copyright ownership and authorship of the logo in connection with such use.

This answer does not constitute legal advice, nor does not create an attorney-client relationship. I am licensed to practice law in Florida only and this answer should not be construed as an offer to practice law outside Florida. For more information on Attorney Conlin's practice, visit http://www.cynthiaconlin.com.