The Associated Press reports that the documents were found by scholars combing through Austrian archives preparing for an exhibition opening today about Mozart's later years in Vienna.
Otto Biba, director of Vienna's musical archives, told the AP that successful professionals lived comfortably on 450 florins a year. Mozart's wages, earned while he lived in the city from 1784 to 1787, would have placed him in the top 5 percent of wage-earners in late 18th-century Vienna.
His income while in Vienna came from public concerts and teaching aristocrats, although his concert-giving income largely disappeared after 1786. Mozart, however, was notoriously bad at managing his money. He was often in debt and forced to borrow, and prone to lending sums to friends and recent acquaintances.
Mozart died in in 1791 and was buried in a common grave, a fact that has also been used as evidence of his poverty (in many accounts it is referred to as a "pauper's grave.") But in fact such a burial appears to have been customary in Vienna at the time.