Can I apply for S1 visa at the same time as my husband applies for his Z type?

Natasha, yes, you can apply for it at the same time as your husband applies for the Z type. The employer doesn’t need to specify it on the invitation letter. Aside from the normal documents you prepare for the S1 type, you also need to provide copies of your husband’s work permit and invitation letter of a duly authorized unit. In this case, you two can apply at the same time.