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: Sam recently lost their job, so they moved in with their friend Chris until they could get back on their feet. Sam buys the groceries ($250 a month), while Chris pays for all other necessary expenses ($1,100 a month). Because Chris pays for more than half of Sam's living expenses, Chris is financially supporting Sam.
Example 2: Every month, Leigh sends $100 to their son, 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, they don't financially support their son.