Alex Kerrigan October 30, 2021 Apartment Investing, Multifamily, Commercial Real Estate RUBS Income: Increasing Profits with a Ratio Utility Billing System Alex Kerrigan October 30, 2021 Apartment Investing, Multifamily, Commercial Real Estate Apartment investors can save big by implementing RUBS (Ratio Utility Billing System). RUBS uses various metrics to calculate a unit’s monthly utility bill, including an apartment unit’s size, amount of bathrooms, and other factors.