The (T) or (S) refers to Taxpayer or Spouse.
Form 8915 Qualified 2016 Disaster Retirement
Plan Distributions and Repayments is required if you had either of these circumstances:
Use Form 8915A if you were adversely affected by a 2016 disaster and you received a distribution that qualifies for favorable tax treatment.
Use Form 8915B if you were adversely affected by a 2017 disaster and you received a distribution that qualifies for favorable tax treatment.
For more information see:
https://www.irs.gov/forms-pubs/about-form-8915-a-and-8915-b
