Yes, one of the covenants made during Baptism is to live according to the law of Tithing. When you are interviewed for Baptism you are asked if you are willing to live by the law of tithing.  
 
The Church will not excommunicate a member for not tithing nor will they force anyone to pay there tithes, but not being a full tithe payer has impacts on ones standing in the Church (such as calling and receiving a temple recondite). 
 
I would like to point out thought that the Law of Tithing is a lower law, based upon the Higher Law of Consecration, where one gives 100% of there income and property to the lord. The Ancient Church lived under this law as well as the early restored Church, unfortunately the membership failed to be able to live this Celestial Law of Consecration and lost many blessings, most importantly the loss of New Jerusalem or Zion, and the lower law of tithing was reinstated.