Why is Stacie's unmarried daughter, who was 25 years old, not considered Stacie's qualifying child?

The reasoning behind Stacie's unmarried daughter, who is 25 years old, not qualifying as Stacie's qualifying child is rooted in the age test stipulations outlined by the IRS. Generally, to be classified as a qualifying child, the individual must be under 19 years of age at the end of the tax year or a full-time student under the age of 24. Since the daughter is 25 years old, she surpasses the maximum age limit for qualifying as Stacie's child under the age test criteria.

Other potential factors that might influence whether someone qualifies as a dependent, such as not filing a joint return, citizenship status, or living arrangements, are not applicable in this situation. The critical disqualification here is the age itself, which directly prevents her from being considered a qualifying child.