For the H-1B and PERM programs, employers must submit requests for Center Director Review/Challenge in writing no more than 30 days after determination. Employers must send their requests for Center Director Review/Challenge to the following address: U.S. Department of Labor Employment and Training Administration Office of Foreign Labor Certification National Prevailing Wage Center Attn: PW Center Director Review 1341 G Street, NW Suite 201 Washington, DC 20005-3105 For the H-2B program, employers must submit requests for CO Review in writing no more than 10 days after determination. Employers must send their requests for CO Review to the following address: U.S.