Personal Legal Names

• A person's legal name is based on the name on her birth certificate and her Social Security number. You can legally change your name, which results in a new name but not necessarily a fictitious name you can use at will.
  
  

Corporate Legal Names

• A corporation, which is considered a legally separate entity, has a legal name determined by the articles of incorporation and its federal tax ID number. This name is used in IRS records and important financial documents.
  
  

Fictitious Names

• Individuals and companies can assume fictitious names, but a person can assume a fictitious name only for business reasons. This is required if a person begins a business that does not directly use his surname. For instance, Bob Smith can start Smith's Automotive Services without having to register a fictitious name, because Bob is using a surname. But if Bob were to start Bob's Automation, he would need to file for a fictitious name because the company name does not include his surname.
  
  

Sole Proprietorships and LLCs

• The owner of a sole proprietorship must typically register a fictitious name for any business that does not include her surname. This is for a business use but is also a personal change, and is often used to protect personal information or manage taxes, disassociating the business from the person who owns and runs it. Creating an LLC is like making a corporation, in that a separate organization is made and has its own legal name.
  
  At times using a fictitious name offers a marketing advantage. Calling a restaurant Gull's Landing can offer more aesthetic value than calling it Mary Smith's. Likewise, if a person has any negative connotation surrounding their name, he can use a fictious business name so that people will not immediately associate the negative name and the business. Other fictitious names allow businesses to open bank accounts separate from their owners' accounts, or allow a business to enter a brand new field of operations without being linked to an older branch or parent company.
  
  

Corporate Fictitious Names

• Corporate fictitious names are not as related to the individual owners of the company as names used by sole proprietors. For instance, a corporation or LLC must file for a fictitious name if it markets or sells under any name except its exact corporate name. Businesses sometimes operate under fictitious names for strategic market demographic purposes. A corporation can have multiple fictitious names for each market it operates in. While state laws vary, many states require both individuals and corporations to file for fictitious names with the government.