My suggestion is to first determine if the aging parent needs to file a tax return.
Use the IRS conversation at https://www.irs.gov/help/ita/do-i-need-to-file-a-tax-return
Click the "Begin" button at the bottom of the page and enter their information.
The result will tell you if they needs to file.
You can also refer to https://www.irs.gov/publications/p501#en_US_2021_publink[phone number removed]
In this link, it is addressed under "Who Must File."
Also https://www.irs.gov/taxtopics/tc553 addresses some more unusual situations regarding a dependent's unearned income.
This will address if they need to file.
If they do not need to file, then determine if you can claim her as a dependent.
Follow the instructions at https://www.irs.gov/help/ita/whom-may-i-claim-as-a-dependent
If both options are possible, the only way to tell which is "better" is to go through the process of calculating the taxes both ways and determine which way results in the least overall taxes.
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If she qualifies as your dependent, claim her and enter her 1095-A on your joint return. If she is a dependent on your return, she can't enter a 1095-A on her return. If she is required to file a tax return, then she should do so and report her 1095-A on her own return - but only if she is otherwise required to file a tax. Whether or not she files depends on her income and the level of support you provided.
Is a dependent required to file a tax return?
If you are entitled to claim her as a dependent, it would provide a $500 credit for Other dependent and not much else. If you claim her as a dependent on your return you will need to file the form 1095-A on your return for her.
However, if she has taxable income of her own she can file a return if nothing more than to get withholdings as a refund. She can file that return and not claim herself as a dependent which would allow you to claim her as a dependent on your return if you qualify based on the answer from @bosso3 above.
If the aging parent is not required to file, can they still file in order to file the 1095-A on their return? No income to report also. I am also able to claim parent as dependent. It just seems complicated to reflect the 1095-A on mine. Thanks