Filing

[Kbsutton]

If I claim my 23 yo who has no income as a dependent can she also file and claim her son as her dependent?

[xmasbaby0]

No.   First of all, a dependent cannot claim to have a dependent of their own.  If your 23 year old can be claimed as your dependent, then the child can also be your dependent if you are supporting both of them.  There is no benefit whatsoever for a person with no income earned from working to file a tax return and claim a dependent.   All of the child-related credits are based on having income from working.  Your child who did not work cannot get earned income credit, childcare credit or the child tax credit by claiming a child.

IRS interview to help determine who can be claimed:

https://www.irs.gov/help/ita/who-can-i-claim-as-a-dependent

https://ttlc.intuit.com/questions/3113432-who-can-i-claim-as-my-dependent  

WHO CAN I CLAIM AS A DEPENDENT?

You can claim a child, relative, friend, or fiancé (etc.) as a dependent on your 2023 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 $4,700 in 2023.
• You provided more than half of their financial support

[Opus 17]

If your 23 year old child and their child (your grandchild) both live in your home, you can probably claim both of them as dependents.

As stated, someone who is claimed as a dependent can't have dependents of their own, and since your adult child has no income, they won't receive any credits or refund even if they claimed their own child.

Also note that,

1. Your 23 year old can be your qualifying child dependent if they are a full time student and live in your home (or are temporarily living at college but considered to live at home).  If they do not live in your home but you pay more than half their living expenses, or if they live in your home but are not a student, they can be a qualifying relative dependent.  Both types of dependent allow you to claim a $500 credit only.

2. Your grandchild can be your qualifying child dependent if they live in your home more than half the year (or more than half the days since they were born if they were born in 2023). This is worth up to $2000 child tax credit depending on your other tax facts.  If they do not live in your home but you pay more than half their living expenses, they are a qualifying relative dependent for a $500 credit.