H1B dependents: can they apply for work permit for 20Hours/week?

I have heard that H1B dependents who are on H4, can apply for a work permit of 20 hours/week. Is this correct? If yes, how and when can this be applied? If not, what are the possible options for my spouse on H4 out there in US?

Thanks!

That is not true. Dependents cannot work until they receive an EAD. Do you have your green card process already initiated?