Do I need to add him as dependent when he never came to US? is he even eligible for ITIN? Will i get any benefit to add him as dependent?
There are tax benefits for claiming him as a dependent If you are eligible to claim him on your US tax return.
There are two sets of rules in claiming someone as a dependent on your tax return. The Qualifying Child rules and the Qualifying Relative rules.
Under the Qualifying Child rules you may be eligible for the Child Tax Credit which is up to $2,000.
Under the Qualifying Relative rules you would be eligible for the Other Dependent Credit which is $500.
But if he does not have a SS number or an ITIN then you cannot enter him as a dependent on your tax return in either case. See this IRS website for ITIN information - https://www.irs.gov/individuals/individual-taxpayer-identification-number
To be a 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, (b) under age 24 at the end of the year and a full-time student or (c) any age and permanently and totally disabled.
3. The child must have lived with you for more than half of the year. Temporary absences while away at college are considered living with you.
4. The child must not have provided more than half of his or her own support for the year.
5. If the child meets the rules to be a qualifying child of more than one person, you must be the person entitled to claim the child as a qualifying child.
6. The child must be a U.S. citizen or U.S., Canada or Mexico resident for some portion of the year.
7. The child must be younger than you unless disabled.
To be a Qualifying Relative -
1. The person cannot be your qualifying child or the qualifying child of any other taxpayer. A child is not the qualifying child of any other taxpayer if the child's parent (or any other person for whom the child is defined as a qualifying child) is not required to file an income tax return or files an income tax return only to get a refund on income tax withheld.
2. The person either (a) must be related to you or (b) must live with you all year as a member of your household.
3. The person's gross income for the year must be less than $4,200 (social security does not count) in 2019
4. You must provide more than half of the person's total support for the year.
5. The person must be a U.S. citizen or a U.S., Canada, or Mexico resident for some part of the year.
6. The person must not file a joint return with their spouse.