If he had income other than from working he might be subject to "kiddie tax."
If the financial aid was more than his tuition, some of it is taxable income.
As others have said, much more detail is needed.
Are you talking about a 2023 tax return? How old was your son on December 31, 2023?
What exactly do you think the error is? Please give exact amounts of income, tax withheld, amount owed, financial aid, and tuition and other education expenses. What other income does he have besides from the part-time job? Did he get a 1098-T?
Did he file as single? Did he check the box saying that someone can claim him as a dependent?
Does he live in Washington or just go to school in Washington and live in another state? What state was the job in?
Has the tax return been filed? If so, was it e-filed or filed by mail? If it was e-filed, was it accepted?
If there is an error, who is going to correct it? Did his stepmother use TurboTax Online or the CD/Download TurboTax software?
