Who should I assign as the designee to discuss my CO taxes if needed. its also asking for a phone number

[NicolleR1]

You can assign any person that you want (this is optional), but you might want to choose a relative, fiduciary, or tax professional to view your tax account, discuss tax matters, and manage certain aspects of your account. The phone number is just so that when they call, they might need to provide their phone number for verification purposes. The CO Dept of Revenue will not call them. 

Third Party Access | Department of Revenue - Taxation