Form SC-40 is an Indiana State form:

SIMPLIFIED FORM FOR LOW INCOME SENIORS

Indiana has a Unified Tax Credit for the Elderly. If you meet the eligibility requirements, you can claim this credit on your Form IT-40 or Form IT-40PNR income tax return.

However, if you aren't required to file an income tax return because your exemptions are more than your federal adjusted gross income, there is a Form SC-40 you can file to claim a refund of your Unified Tax Credit for the Elderly.

Click below for more information: http://www.in.gov/dor/4746.htm