This would only be reported if her has other income and needs to file a return in his name. You do not have to report social security benefits of a dependent on your return
See this explanation from IRS Survivor Benefits Question and Answer. The page is referring to children, but
this is applicable for an adult that is claimed as a dependent as well:
Question:
Are social security survivor benefits for children considered taxable income?
Answer:
Yes, under certain circumstances,
although a child generally won't receive enough additional income to make the
child's social security benefits taxable.
- The taxability of
benefits must be determined using the income of the person entitled to
receive the benefits.
- If you and your child both receive benefits, you should calculate
the taxability of your benefits separately from the taxability of your
child's benefits.
- The amount of income tax that your child must pay on that part of
the benefits that belongs to your child depends on the child's total
amount of income and benefits for the taxable year.
To find our
whether any of the child's benefits may be taxable, compare the base amount for
the child’s filing status with the total of:
- One-half of the
child's benefits; plus
- All of the child's other income, including tax-exempt interest.
If the child is
single, the base amount for the child's filing status is $25,000. If the child
is married, see
Publication 915
, Social Security and
Equivalent Railroad Retirement Benefits, for the applicable base amount and the
other rules that apply to married individuals receiving social security
benefits.
If the total of (1)
one half of the child's social security benefits and (2) all the child's other
income is greater than the base amount that applies to the child's filing
status, part of the child's social security benefits may be taxable. You can
figure the taxable amount of the benefits on a worksheet in the
Instructions for Form 1040
,
Instructions for Form 1040A
, or in
Publication 915
.
