It is standard industry practice (and my policy as well) not to release work files. What you buy from me is a one-time finished product — a trade show banner, a magazine ad, a brochure, or a product photo in a flattened format such as jpeg or png.
According to the Graphic Artist’s Guild Ethical Guidelines and copyright law, everything a designer designs is protected by creative copyright. The source file belongs to the designer unless it is transferred to the client in writing. The client pays for the use of the work but not for editable files.
In addition, working files contain components such as stock photography, clip art, and fonts that have been licensed for use by the designer. You, the client, would then have to pay to license those items.
Therefore I retain all work files, unless additional arrangements are made, including additional charges.
If you should ever want any of my editable files to be worked on by another designer, these files would be available for purchase at an additional charge. This would include Adobe InDesign files for page layout, and layered (unflattened) Photoshop and Illustrator files for images. However, these files, especially older files, may have been created in versions of the software that are now outdated, and may be unusable. At the very least, another designer would have to have the same software the files were created in to be able to open the files.
You would also be within your rights to hire another graphic designer/photographer to recreate my work from scratch. It would be your prerogative to decide whether that option would be more cost-effective than purchasing an editable file from me. For instance, having another designer recreate a simple magazine ad from scratch might cost less than purchasing the original work file from me to make further edits. However, a more complex project, such as a multi-page brochure, may prove more cost-effective to purchase my work file to have another designer make minor changes to.
To clarify: Just as you would contract a wedding photographer for a package of wedding prints, what you pay for is just the prints — you are not entitled to the negatives as well. The photographer keeps them as making prints from negatives is how they earn a living. If you would like to purchase the negatives to take elsewhere for prints, the photographer would charge an additional amount for the negatives.
For more information:
Why Designers Don’t Give Up their Files
AIGA | the professional association for design
DESIGN BUSINESS +ETHICS