I have the new Iris 3 tier project case holder and it works perfectly for my monthly bills.  I have one labeled for my monthly household bills, one for credit card receipts and one for bills related to my beach house. 

As I process my daily mail and receipts, I place each piece in the appropriate project case.  When the time comes to process them, I pull the project case out and everything I need is right there together.  The case can travel with me to another part of the house or in the car if I am working on it while I travel.  It saves me time as I no longer have to search for all related items when I am paying bills.  And, it keeps me organized to readily find whatever bill or receipt I am looking for.

Note: The 3-Tier Project Case holder includes 3 Project Cases.  It is also available as a slim size.