 It was only in 1811 that they received the legal status of citizens.However, as Paul Arnsberg writes in his book, "Geschichte der Frankfurter Juden", 
For the Grand Duchy, emancipation meant that it would lose the annual protection money from the Jews, which it could ill afford.Therefore a "tax commutation payment" was determined, and the Jews of Frankfurt had to purchase their freedom with 440,000 gulden.