First Presidency in 2006 states those practicing polygamy will be excommunicated.
First Presidency, Letter to Church Leaders in the United States and Canada, February 17, 2006, rep. in Gary James Bergera, comp., Statements of the LDS First Presidency (Salt Lake City: Signature Books, 2007), 328–329
Polygamy was officially discontinued by The Church of Jesus Christ of Latter-day Saints in 1890. Any Church member adopting the practice today is excommunicated. Those groups which continue the practice in Utah and elsewhere have no association whatever with The Church of Jesus Christ of Latter-day Saints, and most of their practitioners have never been among our members.