Cases governed under ERISA (Employee Retirement Income Security Act) require you to file at least one administrative appeal to the insurance company. Once that appeal, and any subsequent appeals are exhausted, you then have the right to file a lawsuit.  It is typically recommend that you file an appeal and at that point, decide whether you want to file a lawsuit or pursue a second administrative appeal, if allowed.  Sometimes, it is better to work with what is already in the file, rather than giving the insurance company more chances to strengthen their case. On the other hand, if you case has some weak spots or issues, you may want to consider filing a second appeal to address those problems before filing a lawsuit.