What does "financially support another person" mean?
One requirement to claim a dependent is that you must provide more than 50% of their support, which is the cost of basic life necessities such as food, lodging, clothing, medical and dental care, education, transportation, utilities, and so forth.
To determine this, compare how much you spend on this person's necessities with how much they (or somebody else) contributes.
Divide per-household costs like utilities, groceries, and lodging by the number of household members to determine the per-person cost.
If your mortgage is paid off, use the fair rental value of your home to figure the lodging expense.
If you are paying more than 50% of another person's necessary living expenses, you financially support that person.
Example 1: Karl's friend Hannah, who recently lost her job, moved in with Karl so she could get back on her feet while looking for another job. Hannah buys their groceries ($250 a month) while Karl pays all other necessary expenses ($1,100 a month). Karl is financially supporting Hannah because he pays more than half of Hannah's living expenses.
Example 2: Every month, Leigh sends $100 to her son John, who is incarcerated at the state prison. But because the cost of lodging, food, utilities, and medical care provided by the prison system far exceeds Leigh's contribution, she does not financially support him.