My daughter turned 18 in August and then began to work in Sept do I still claim her?

[Mike9241]

tests to claim her as a qualifying child or qualifying relative

you can claim her as a qualifying child if all these tests are met
• she has the same principal abode as you for more than ½ the tax year. Temporary absences like for school are ignored
• if she is not a full-time student, she's under 19 at the end of the tax year. If a full-time student, he's under 24 at the end of the tax year.
• she hasn't provided over ½ her own support
• she didn't file a joint return unless there was no tax liability but merely filing joint to facilitate refund of taxes withheld or estimates paid

or you can claim her as a qualifying relative if all these tests are met
• her gross income for 2021 less than $4,350
• you provided over ½ her support
• she isn't a qualifying child of another taxpayer

[xmasbaby0]

IRS interview to help determine who can be claimed:

https://www.irs.gov/help/ita/who-can-i-claim-as-a-dependent

https://ttlc.intuit.com/questions/3113432-who-can-i-claim-as-my-dependent  

MY DEPENDENT HAD A JOB

If your dependent has a W-2 for his after-school job, summer job, etc. you do not include the information on your own return. You can still claim your child as a dependent on your own return.  He/she can file his own return for a refund of some of his withheld wages (he won’t get back anything for Social Security or Medicare), but MUST indicate on it that he can be claimed as a dependent on someone else’s return.  (Supervise this closely or prepare it for him!)

If your dependent’s earnings were over $400 and were reported on a 1099Misc or 1099NEC then he must file a return and pay self-employment tax for Social Security and Medicare.

You might also want to use free software from the IRS Free File versions:

https://apps.irs.gov/app/freeFile/