It's 16 for the Child Tax credit, not 17.
You can still claim your child, as a dependent. What you can't claim is the Child tax credit. This comes as a big surprise to many parents the year their child turns 17. A child over age 16 no longer qualifies for the Child Tax credit (CTC). Although a child can still be a student dependent through age 23, and a qualifying child for EIC, the Child Tax Credit expires the year they turn 17 and you no longer get the $2000 CTC. Instead you will get the non-refundable (up to) $500 Other Dependent Credit.
