It is the PA tax forgiveness form.
Can you explain Pennsylvania's Tax Forgiveness program?
The Tax Forgiveness Program allows low income taxpayers to either reduce or eliminate their tax liability through tax forgiveness credits. To receive tax forgiveness, a taxpayer must complete the tax forgiveness schedule and file a PA-40 return. The level of tax forgiveness is based on the income of the taxpayer and the number of dependents the taxpayer is able to claim.
To see if you qualify, check the PA-40 instruction booklet and complete the Schedule SP.