Forget about setting up a post office box in Switzerland or Grand Cayman Island. The small village of Mark, Ill., is allowing one fuel oil company to save about $23 million in sales taxes, interest and penalties.

That company is the Hartney Fuel Oil Co., which has been fighting a long-running battle with the Illinois Department of Revenue. Hartney relocated some of its operations in 2003 from the Chicago suburb of Forest View to some space it rented from a painting company and later to a former house in Mark. That enabled it to escape the relatively high sales tax rates of Cook County by moving some of its offices to Putnam County, where the tax burden is less, according to the Chicago Tribune.

Putnam County even reimburses half of its share of state sales tax revenue back to Hartney as a further sweetener.

That has rattled the Chicago-area tax authorities, who are worried that many more businesses will do the same thing.