If you would like to authorize a tenant or someone else to pay your utility bills, here is a sample template you can use to write an authorization letter for utility bills.
Subject: Authorization for Utility Bill
This letter is in relation to [Name], who resides at a property located in [State/city]. I authorize him/her to live at [Address], a premise whose utility bill comes in my Name. It is hereby confirmed that utility bills will continue to come in my Name.
I am enclosing the identity proof of the authorized person along with the utility bill for your reference.
Please feel free to contact me on [Email/contact number] in case of any query concerning this letter.