Gov and search for withholding requirements for updates, online tools, and more information, including: Forms and Publications Form 587, the payee agrees to promptly notify the withholding agent of any changes in the facts.To aid you in completing the STD 686 Employee Action Request (EAR) form as a new employee or to update your withholdings, the following is a Quick Start Guide. The due dates for California backup withholding are different than federal backup withholding due dates.