These taxpayers must have earned income of at least $2,500 to receive a refund, even if they owe no tax, with the additional child tax credit. The credit begins to phase out at $200,000 of modified adjusted gross income. The Child Tax Credit (CTC) is designed to give an income boost to the parents or guardians of children and other dependents. It only applies to dependents who are younger than 17. The credit is worth up to $2,000 per dependent, but your income level determines exactly much you can get. You can only make a new claim for Child Tax Credit if you get the severe disability premium or got it in the past month and are still eligible for it. If your child is 16, you can claim up until 31 August after their 16th birthday. If they are in approved education or training, you can claim until their 20th birthday.