To file the LCA prevailing wage needs to be established regardless of size of company; however, if you mean whether they need to file a request with OFLC National Process Center for determination to be made, the answer is not necessarily. Request with OFLC is only one of the many ways to determine prevailing wage. Depending on your occupation, other methods may be available. If the wage is lower than the prevailing wage, the LCA will be rejected.
Also note that whether a company is dependent or not is not based on the number of employee but the number of foreign employee they employed. A small company of 15-20 employee will be dependent if it employs 8 H1B emplyoyees.
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