When did the Nazis forbid the Jews to emigrate?

Until August 1941 Jews were allowed to emigrate from Germany and from Nazi-occupied Western Europe, provided they could find a country to accept them and could actually travel there. They were able to pay the fares (including meals and so on) in advance in Germany, but they were not allowed to take much money with them and had to pay for permission to leave Germany.

In September 1941 Heydrich ordered a halt to all Jewish emigration - in anticipation of the Final Solution.