My daughter turned 18 in September and doesn't work and still in school why don't I get the full child tax credit

For the child tax credit the child must be under the age of 17 on 12/31/2024.  If the child is age 17 or older then they are only eligible for the Other Dependent Credit of $500.

You lost the child tax credit when she turned 17.   You only get the CTC  for children 16 or younger. There are no exceptions    After that you get the $500 credit for other dependents.

 

 

https://ttlc.intuit.com/turbotax-support/en-us/help-article/taxation/child-tax-credit/L2lNhfGDl_US_en_US?uid=m68dfq2u

 

https://ttlc.intuit.com/turbotax-support/en-us/help-article/taxation/additional-child-tax-credit/L6xFeMFEf_US_en_US?uid=lqnuygah

https://www.irs.gov/help/ita/does-my-childdependent-qualify-for-the-child-tax-credit-or-the-credit-for-other-dependents