To update your tax withholding, you must do so in ADP Workforce Now on a computer with a secure internet connection (you cannot update your tax withholding through your ADP app). For help registering for an ADP Workforce Now account, see How do I register for ADP Workforce Now?
Once you've logged in to ADP Workforce Now on a computer with a secure connection, navigate to Pay>Tax Withholdings in the top menu. From there, select the Federal link. You can change your marital status, exemptions, and additional amount withheld.
If you've moved to a new state and need to make changes to state or local tax withholdings, you will need to request a market change. Learn more about market changes: How do I change my Shiftgig market?