Question: When does the 2017 tax plan take effect?
Disambiguated questions and answers: question: When will the 2017 tax plan begin to take effect?
When will the 2017 tax plan begin to affect people?
answer: January 1, 2018
tax filing - April 17, 2018
Natural Questions answer: January 1 , 2018 (from the Wikipedia article "Tax Cuts and Jobs Act of 2017")