If your 21 year old is a full-time student then the student can be claimed no matter how much they earned. But not the 20 year olds------it does not matter if you paid over half their support. If their income was more than $4300 for 2020 they are not qualifying children or qualifying relatives and you cannot claim them.
WHO CAN I CLAIM AS A DEPENDENT?
You can claim a child, relative, friend, fiance (etc.) as a dependent on your 2020 taxes as long as they meet the following requirements:
Qualifying child
•They are related to you.
•They cannot be claimed as a dependent by someone else.
•They are a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
•They are not filing a joint return with their spouse.
•They are under the age of 19 (or 24 for full-time students).
- No age limit for permanently and totally disabled children
• They live with you for more than half the year (exceptions apply).
Qualifying relative
•They don't have to be related to you (despite the name).
•They cannot be claimed as a dependent by someone else.
•They are a U.S. citizen, resident alien, national, or a Canadian or Mexican resident.
•They are not filing a joint return with their spouse.
•They lived with you the entire year.
•They made less than $4300 (not counting Social Security)
•You provided more than half of their financial support. More info
**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.**
