If you already got the 3rd stimulus for claiming him in 2020 you do not get it again. Nor do you get the $1400 again if you already got it for your daughter. If you did not get the 3rd stimulus for your FIL then you can get it as a recovery credit for 2021 for dependents who can be claimed on your 2021 return. For a qualifying relative you also get the non-refundable $500 credit for other dependents. It reduces tax you owe--it is not a refund
https://ttlc.intuit.com/questions/4499708-what-is-the-500-credit-for-other-dependents-family-tax-cre...
There are two kinds of dependents---qualifying child and qualifying relative. Your FIL can be a qualifying relative. You have not provided details about your daughter so we do not know which kind she could be.
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
When you add someone as a dependent, we'll ask a series of questions to make sure you can claim them.
Related Information:
•Does a dependent have to live with me?
•What does "financially support another person" mean?
•Can I claim a newborn baby?
**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.**
