The parent's marginal tax rate will be applied to most of the taxable scholarship (the so called "kiddie tax"). About $4600 will not be taxed at all, because of the increased standard deduction.
Scholarships are a hybrid between earned and unearned income. It is earned income for purposes of the $14,600 filing requirement (2024) and the dependent standard deduction calculation (earned income + $450). It is not earned income for the kiddie tax and other purposes (e.g. EIC). For grad students and post grad fellows, scholarship, stipend and fellowship income is earned income ("compensation") for IRA contributions.
You might want to consider having him pay even more tax:
There is a tax “loop hole” available to claim an education credit, for the parents of students on scholarship. The student reports all his scholarship, up to the amount needed to claim the American Opportunity Credit (AOC), as income on his return. That way, the parents (or himself, if he is not a dependent) can claim the tuition credit on their return. They can do this because that much tuition was no longer paid by "tax free" scholarship. You cannot do this if the conditions of the grant are that it be used to pay for qualified expenses.
Using an example: Student has $10,000 in box 5 of the 1098-T and $8000 in box 1. At first glance he/she has $2000 of taxable income and nobody can claim the American opportunity credit. But if she reports $6000 as income on her return, the parents can claim $4000* of qualified expenses on their return.
Books and computers are also qualifying expenses for the AOC. So, extending the example, the student had another $1000 in expenses for those course materials, paid out of pocket. She would only need to report $5000 of taxable scholarship income, instead of $6000.
Taxable scholarship goes on line 8r of Schedule 1.
*The AOC is 100% of the first $2000 of tuition and 25% of the 2nd $2000. Declaring only $2000 more scholarship (instead of $4000) might be an alternate option; usually not.
