Are Social Security underpayments taxable?

Did you receive a SSA-1099? The Social Security Benefit Statement (SSA-1099 form) is used to notify payees and the IRS that SSA benefits received during the year may be taxable.

Here is an excerpt from http://www.segurosocial.gov/oig/ADOBEPDF/A-03-03-13014.pdf

Death underpayments are still Social Security benefits, and only a maximum of 85 percent of Social Security benefits may be subject to income tax.