Self employed

Not sure what you mean by "not consistently a full-time college student"   --- please explain more.    Was she age 19 at the end of 2021?   Was she a full-time student for at least five months?

In order to claim the student as a dependent the student had to be a full-time student for at least five months of the tax year  (even if the five months was part of August to the end of the year).   If your dependent was a full-time student then it does not matter how much the student earned----they can earn more than the standard deduction amount and still be claimed as your dependent.   They can file their own tax return and seek a refund of federal and state tax withheld, but must say on the return that they can be claimed as someone else's dependent.  They will not get back anything that was withheld for Social Security or Medicare--only federal or state tax could be refunded or partly refunded, depending on the amount.

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  

WHO CAN I CLAIM AS A DEPENDENT?

You can claim a child, relative, friend, or fiancé (etc.) as a dependent on your 2021 taxes as long as they meet the following requirements:

Qualifying child

• They're related to you.
• They aren't claimed as a dependent by someone else.
• They're a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
• They aren’t filing a joint return with their spouse.
• They're under the age of 19 (or 24 for full-time students).
• No age limit for permanently and totally disabled children.
• They lived with you for more than half the year (exceptions apply).
• They didn't provide more than half of their own support for the year.

Qualifying relative

• They don't have to be related to you (despite the name).
• They aren't claimed as a dependent by someone else.
• They're a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
• They aren’t filing a joint return with their spouse.
• They lived with you the entire year (exceptions apply).
• They made less than $4,300 in 2021.
• You provided more than half of their financial support.

When you add someone as a dependent, we'll ask a series of questions to make sure you can claim them. There may be other tax benefits you can get when y