When a corporation pays salary to a shareholder-employee beyond what is considered to be reasonable compensation, how

Question:

When a pays salary to a shareholder-employee beyond what is considered to be reasonable compensation, how is the salary in excess of what is reasonable treated for tax purposes? Is it subject to double taxation?
Corporation
A Corporation is a legal form of business that is separate from its owner. In other words, a corporation is a business or organization formed by a group of people, and its right and liabilities separate from those of the individuals involved. It may...