If I do not use all my benefit, can I give it to my co-worker?

No! Your Transit Benefit belongs to you and to no one else.

It is against the law to sell or give your fare media to someone else. The federal Transit Benefit was designed to assist employees with public transportation costs and support initiatives that cut-down on air pollution and relieve traffic congestion. The Transit Benefit is not transferable. It is not to be loaned, given away or sold. When you retire, leave the agency, or otherwise separate, you must return all unused fare media to your employing agency. This includes accepting employment with another federal agency. Each employer funds their own program. You must withdraw from the first agency and apply with the new agency.