My son can get a big refund if I do not declare him as a dependent, but will I get into trouble if I declare him as dependent next year?

[merson_1]

he had unearned income in 2020 that is causing him to be taxed at my rate (he is a full time college student)

[MinhT1]

You do not pick and choose whether you claim your son as a dependent.

If he is under 24 and a full time student and you provide more than half of his support for the tax year, you can claim him as a dependent. If you do not claim him, then you lose the Other dependent credit of $500 and you cannot claim his education credit from his form 1098-T.

On his own tax return, he is asked the question whether he paid more than half of his own support. If the answer is No, then he has to say that he can claimed as a dependent by someone else. And he will not be eligible for the first two stimulus payments. As someone who can be claimed as a dependent but is not actually claimed, he can claim the non-refundable part of the American Opportunity credit, but not the refundable part.

[Mike9241]

you must be referring to the kiddie tax

it doesn't matter whether you claim him or not. the 8615 goes with his return. 

so you won't get into trouble. he could. 

Who Must File
Form 8615 must be filed for anyone who meets all of the following conditions.
1. You had more than $2,200 of unearned income.
2. You are required to file a tax return.
3. You were any of the following:
a. Under age 18 at the end of 2020

b. Age 18 at the end of 2020 and didn’t have earned income that was more than half of your support, or
c. A full-time student at least age 19 and under age 24 at the end of 2020 and didn’t have earned income that was more than half of your support.
4. At least one of your parents was alive at the end of 2020.
5. You don’t file a joint return for 2020.