If you are an employer wishing to sponsor (or petition) for a foreign national to work in the United States on a permanent basis, you must file Form I-140, Immigrant Petition for Alien Worker. Some highly qualified alien workers can self-petition I-140.

Before I-140 can be filed, labor certification must be filed and approved in most categories. Labor certification, where applicable, certifies that there are not sufficient workers who are able, willing, qualified, and available at the time and place where the alien is to be employed and that employment of the alien, if qualified, will not adversely affect the wages and working conditions of similarly employed U.S. workers.

If the application is labor certification based, the priority date is the date the Department of Labor receives the application. If the application is not labor certification based, the priority date is the date when USCIS receives I-140 application.

I-485 (also EAD and Advance Parole) can be applied for at the same time as applying for I-140, provided the priority date is current. You can periodically check the visa bulletin to check the priority dates.

Getting the I-140 approved does not change the applicant's non-immigrant status. The applicant is still on the same non-immigrant status before I-140 was approved.

An I-140 petition approval is entirely contingent upon the employee remaining in the same job. If the job changes, then a new I-140 is required. This is true whether the I-140 is sponsored or self petitioned, though in the case of a self-petitioned I-140, a new job that is substantially similar would continue the validity of the petition.

Premium Processing of I-140 is available in certain classifications.

• Application fee must be sent with the application.
  There is no biometric fee.
  
  Fee details
  
  
• Form I-140, Immigrant Petition for Alien Worker.
  Appropriate petition type must be mentioned in the section 2 depending upon the employment based classification (EB1, EB2, EB3) and subcategory applied for.
  
  
• Approved labor certification, whenever applicable.
  
  
• For petitions that require job offers, evidence that the prospective U.S. employer has the ability to pay the proffered wage. The employer can submit copies of annual reports, federal tax returns, or audited financial statements. Alternatively, if the employer employs 100 or more workers, a statement from a financial officer of the organization which establishes the ability to pay the wage may be submitted. Additional evidence, as appropriate, such as profit/loss statements, bank account records, or personnel records may be submitted.
  
  
• In certain categories, job experience letters from your former employers on their business stationary. The experience letters don't necessarily have to be from your former bosses. Even your colleagues who know about your experience can write those letters. If your colleagues have moved to different jobs at the present, they can use the business stationary of their current employer. Letters from the HR department merely stating the duration of employment won't do. Any other documents which would prove the credentials/qualifications for the job also should be submitted.
  
  
• Category specific documents
  • EB-1, Extraordinary Ability
    
    
  • EB-1, Outstanding Professors or Researchers
    
    
  • EB-1, Managers and Executives
    
    
  • EB-2, Exceptional Ability
    
    
  • EB-2, Advanced Degree Professionals
    
    
  • EB-2, National Interest Waiver
    
    
  • EB-2, Physicians in Underserved Areas
    
    
  • EB-3, Skilled, Professional, Other Workers