The bill would creates a temporary credit for non-child dependents: It would allow parents to take a nonrefundable $500 credit for each non-child dependent whom they're supporting, such as a child 17 or older, an ailing elderly parent or an adult child with a disability.
http://money.cnn.com/2017/12/15/news/economy/gop-tax-plan-details/index.html at #6.
[Answer edited to add word nonrefundable as indicated in actual Conference bill].
