My oldest son is 21, full-time college student, has earned >$4,150 and lives at a school away from home for all of the year except summers. And, we provide more than half of his support.
Turbotax asked me how many months he lives at home and I answer (3). Apparently because of this (and his income) I can't claim him as a dependent. However, the IRS website implies that he is considered "temporarily absent" if he is gone due to education, and those months could be still considered living with us which would appear to still qualify him as a dependent.
Why does turbotax not seem to allow me to input the fact that he lived away from us, but was absent for one of these special circumstances?
Because it was a temporary absence, you need to report he lived a home all of the months he was away at school.
TurboTax does not consider the time at school living away from your home because the program is well aware that the IRS allows you to claim college students as dependents and can include the months at school as living in your home. There should be a better explanation and it has been passed to the programmers.