Klari, they are not going to tell you about the tax situation because it varies for citizens of different countries. It is up to you to find out what the tax laws are for a German citizen such as how long you have to be a Qatar resident, if you are allowed to continue to own property in Germany, how many days/weeks/months you must be out of your country to qualify, etc. Please do your homework, I don't want you to be unhappy here or make an unwise decision.
Mandi