Landlord’s have gone to fixed CAM to reduce administrative expenses and disputes with their tenants. The government could accomplish the same by going to a flat tax – no need for complicated tax regulations that create unintended consequences; no need for intrusive audits where the government is at odds with its constituents; in fact maybe no need for the IRS. Take for example the so called "self-rental rule." The Code ( Reg. 1. 469-2(f)(6) if your are keeping score at home) provides (unfairly) that if a taxpayer owns property that it rents to a company in which it has an ownership interest, then any rental loss is passive, but any rental income is active. Really?  This means the loss in the first year cannot offset against  income in the second year.  In fact the loss can never be used at all unless the taxpayer has some passive income from an unrelated deal not involving the rental of property to any entity in which he or she has an interest. Classic case of tails, the taxpayer loses and heads, the IRS wins.