Professional Liability Insurance (Errors and Omissions Insurance)  is your most critical coverage.  Professional liability coverage protects you against loss from a claim of alleged negligent acts, errors or omissions in the performance of your professional services. This might include loss of client data, software or system failure, claims of non-performance, or negligent oversell.  Be sure your professional liability policy includes the following key features:

• Coverage includes legal defense cost.   Professional liability insurance will pay for any resulting judgments against you including court costs up to the coverage limits on your policy.
  
  
• Coverage extends to both W2 employees and 1099 subcontractors.  Coverage should protect your company from claims resulting from the work done by 1099 subcontractors on your behalf. (It is important to note that 1099 personnel need their own errors and omissions insurance because your policy does not defend them if they are sued separately or in addition to you.)
  
  
• Optional coverage for allegations of Copyright Infringement and Intellectual Property Infringement.  Intellectual Property Infringement coverage protects you against claims alleging copyright infringement. Software, systems or processes are some of the most commonly known "intellectual properties."
  
  
• Personal Injury.   Personal injury protects you against claims of libel, slander, and invasion of privacy.
  
  
• Worldwide coverage if the suit is brought in the USA.
  
  

Professional liability coverage may be described in your contract in this way  "Contractor will maintain at its expense: Professional Liability Insurance in the amount of $1,000,000 including coverage for errors and omissions caused by Contractor's negligence in the performance of its duties under this agreement."