There is not a Disability Benefits Deduction on a federal tax return. Are you referring to a state tax return?
There is no "disability benefits deduction" section. Social Security disability is taxable income if you have other income. If the SS is your ONLY income you do not have to file a tax return at all unless you have a 1095A for marketplace health insurance.
If you have other kinds of income in addition to the SS, you may need to file a return.
You need to file a federal return if half your Social Security plus your other income is
Single or Head of Household $25,000
Married Filing Jointly $32,000
Married Filing Separately $0
Who has to file?
http://www.irs.gov/uac/Do-I-Need-to-File-a-Tax-Return%3F
Go to Federal> Wages & Income>>Retirement Plans and Social Security (SSA1099 and 1099RRB) to enter your SSA1099.