What is the ages for dependents to received credit for them when filing Income tax ?

Old enough to breath air directly in their lungs...

Meaning by my understanding they can be claimed in the year they are born.

Don't forget you need an SSN or TIN for any claimed dependents.

If you mean at what age does it stop, the answer is: it depends, and in some cases, it never ends. Without listing all the different ages, you tell us what you have, who lives under your roof at least half the year, is supported by you more than half, is a full time student, or is disabled.

The Child Tax Credit stops when the child turns 17.

The Earned Income Credit stops when the child graduates high school and starts working, or graduates college and starts working.

The American Opportunity Credit can now be claimed for four years by the college student or the student's parents.