Wives, husbands, and unmarried children under the age of 21 are considered dependents of H-1B workers on H4 visa.  Generally, H4 holders are not allow to work, except for certain H-4 dependent spouses of H-1B nonimmigrants meeting the following requirements:

• The H1B nonimmigrant is the principal beneficiary of an approved Form I-140, Immigrant Petition for Alien Worker; or
• The H1B nonimmigrant has been granted H1B extension because his/her green card process was started at least 365 days prior to the day when he/she reach the six-year limit and was still pending