It is saying that my son is too old to claim. He turned 18 in December but he is still living with me and is in school. How do i fix this?

[DoninGA]

Go back to the My Info section of the TurboTax online program.  Edit the dependent and review your answers.  Make sure you selected that the dependent lived in your home for the Whole year.  That the dependent did Not provide over one-half of his own support.  Verify the date of birth is correct and in the correct format, MM/DD/YYYY.  Make sure that you did Not check the box labeled "Not valid for employment" when entering his Social Security number.

If all is correct then delete him as a dependent and re-enter.

[maglib]

@angels_eyes_19 Go back through the personal info interview. I am betting you entered his birthday with only a 2 digit year or answered a section wrong such as Did you indicate the child lived with you for the whole year, Do NOT check the box for the Social Security number being not valid for employment?  ensure you indicate that the child did NOT provide over one-half of their own support.

[SusanY1]

You are eligible to take the other dependent credit for your son but not the child tax credit which ends at age 17 (not 18).  After double-checking the entries as described above, check to see if you are at least getting the $500 other dependent credit.  If the software is just indicating that you don't qualify for the $2000 child tax credit, it is working as intended.