You son needs to amend his return after it has been fully processed to say that he CAN be claimed as someone else's dependent. It seems you nor your son understood that an 18 year old can be claimed as a dependent no matter how much he earned. You can claim him as a qualifying child dependent until the tax year when he turns 24 if he is a full-time student--no matter how much he earns.
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 you claim a dependent.
Related Information:
If your son received the $1400 stimulus as part of his refund he is going to have to pay it back---he was not eligible to receive it. Dependents are not eligible to receive stimulus checks. When he amends he will owe it back.
Your own return claiming him as a dependent will have to be mailed, as stated earlier by Champ Bsch447.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
