What's at stake.
If Pennsylvania opts in, donations made by Pennsylvanians can be directed to PA-listed SGOs, and the scholarships funded by those donations go to PA students. Funds can support tuition at private schools, tutoring for public school students, special education services, books and supplies, after-school programs, and educational therapy. Federal law allows scholarships to cover students at both public AND private schools — meaning EFTC opt-in benefits the existing PA public school system as well as private and parochial schools.
If Pennsylvania does not opt in, Pennsylvanians can still claim the federal EFTC credit by donating to SGOs in opted-in states. Those donations still get the donor the tax credit. The scholarships, however, go to students in those other states. The result is a real net transfer of resources from Pennsylvania to other states' education systems — every year the Commonwealth declines to opt in.