You cannot claim a dependent who files a joint return with a spouse. Why are you only wanting to claim your mother? Do your parents live apart? Or together? There is no such thing as filing "married but single" so you must mean married filing separately.
Share some other details----what income do your parents have? If they file a joint return they are eligible for the stimulus checks. If you claim your mother as a dependent she is not eligible for any stimulus checks at all. And what you "get" for claiming her would be a $500 credit for other dependents and perhaps the $1400 3rd stimulus check.
You say you have been supporting your mother---did you pay for over half her support? Or was she supported by your dad as well? You say she was not working...Did she receive any unemployment?
**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.**
