The interview questions are very good at determining if a person is your dependent and how to file.
If he is your son, answer that he is your son.
Here are the requirements for a "Qualifying Child"
Qualifying
Child
1. The child must be your son, daughter,
stepchild, foster child, brother, sister, half-brother, half-sister,
stepbrother, stepsister, or a descendant of any of them.
2. The child must be (a) under age 19 at
the end of the year and younger than you (or your spouse if filing jointly),
(b) under age 24 at the end of the year, a student, and younger than you (or
your spouse if filing jointly), or (c) any age if permanently and totally
disabled.
3. The
child must have lived with you for more than half of the year.
4. The
child must not have provided more than half of his or her own support for the
year.
5. The child must not be filing a joint
return for the year (unless that joint return is filed only to claim a refund
of withheld income tax or estimated tax paid).
TO CLAIM HEAD OF HOUSEHOLD:
To be considered
a qualifying child, (FOR YOU TO CLAIM HEAD OF HOUSEHOLD) the child must meet
the criteria in each of the following categories:
- The child must be your biological
child, stepchild, foster child, sibling, step sibling, half sibling, or a
descendant (child, grandchild, great grandchild, etc.) of one of these
relatives.
- The child must have lived within your
home for more than six months during the tax year.
- The child needs to be younger than you.
- As of the end of the tax year, the
child must be under 19 if he is not a student, or under 24 if he is a
full-time college student.
- The child must not have paid for more
than half of his living expenses during the tax year.
If your dependent does
not meet the criteria to be a qualifying child, you may still qualify to file
as head of household. The following relatives are considered qualifying
dependents for the head of household filing status as long as you provided more
than half of her financial support and she lived with you for more than half of
the year:
Your biological child,
stepchild, foster child, sibling, step sibling, half sibling or a descendant
(child, grandchild, great grandchild, etc.) of one of these relatives who is
permanently and totally disabled, even if he or she does not meet the age
requirements to be a qualifying child.
https://turbotax.intuit.com/tax-tips/family/guide-to-filing-taxes-as-head-of-household/L4Nx6DYu9
