A student is asking about zakaah; her income is $400 per month
Question

                I am a student who wishes to know when Zakat is due? If I make about $200-$300 dollars every two weeks do I have to pay Zakat? What is the minimum money a person has to make in order to pay Zakat? Where do I give Zakat to? Does it have to be to a muslim/ and please give me examples of places in Kaafir countries where I can give Zakat (ex. mosques)
Praise be to Allah.1-The time when zakaah 
  is due is when you have kept the money for a whole year. Then zakaah becomes 
  due, and the rate is 2.5%. This amount that you get every two weeks is not subject 
  to zakaah unless you have kept it for a whole year, or it is income from a business 
  for which the time has come to pay zakaah. 
2-Pay your zakaah 
  in the country in which you live, if there are poor people there. If there is 
  another country where there are poor people who are in greater need than people 
  in your country, then it is OK to give your zakaah to them. 
3-Yes, the one who 
  receives the zakaah has to be Muslim, except in the case where there is a kaafir 
  whom we want to encourage to become Muslim. If we think that that is most likely 
  to encourage him to become Muslim, it is permissible for us to give zakaah to 
  him.  
Shaykh 
  Sa’d al-Humayd.  
This 
  applies if that kaafir has a high status among the kuffaar and we hope that 
  by his becoming Muslim his people, tribe or clan will also become Muslims.  
The lowest amount at 
  which zakaah becomes due varies according to the type of wealth, whether it 
  is gold or silver. You are undoubtedly asking about an amount of currency such 
  as dollars. It appears that the amount mentioned in the question will be subject 
  to zakaah if it is kept for a whole year, because it is more than the nisaab. 
  For more information on the nisaab see Questions #2795 
  and 64.