If the corporate name you choose is already in use when you file your articles of incorporation, the secretary of state's office will reject your articles of incorporation. You can call the secretary of state's office to find out in advance whether a particular name is available. If the name you have chosen is available, see if the state will let you reserve it. Most states will allow you to reserve a corporate name for a period of time, provided that the name isn't already in use or already reserved. Most state statutes specifically identify which descriptions can be used.
S corporations are subject to the same name rules that a regular corporation is subject to.
An S corporation does not have to indicate its status as an S corporation in its name. An S corporation's status as an S corporation only has to be identified when the corporation is filing its federal income tax return, and, in some instances, when the corporation is filing its state income tax return. Professional corporations are generally subject to the same name rules that apply to corporations with one exception. Most state statutes specifically identify which descriptions can be used.