Yes. To change an electrical panel you need to:
Have your power company turn the power off to the home.
This requires a permit.
Only a person or company that has a Masters License can acquire the appropriate permits.
In Maryland, specifically, there are lots of limitations on what a homeowner can and cannot do without a permit.
Anne Arundel County Department of Inspections and Permits
Baltimore County Department of Permits, Approvals and Inspections