Who is entitled to claim Diane’s grandmother as a dependent?

In this scenario, understanding the dependent eligibility criteria is crucial. To claim someone as a dependent, the person claiming must provide a significant amount of financial support for that individual. Typically, the IRS guidelines specify that a dependent must receive more than half of their support from the taxpayer during the year.

Diane's grandmother must also meet certain other requirements, including being a qualifying relative rather than a qualifying child. For a person to qualify as a dependent relative, they must live with the taxpayer for the entire year, or they must be a relative that the taxpayer provides support for.

If the support provided by Diane and her brother is not sufficient to meet the “more than half” standard, neither can claim the grandmother as a dependent. Additionally, unrelated individuals providing support cannot directly claim that individual as a dependent unless there is significant financial support from those unrelated parties under different circumstances. This reinforces the idea that without meeting the support requirements, it is not possible for anyone to claim Diane’s grandmother as a dependent.