If a person completes the residency requirements under section 306¹ or if a nonresident realizes income attributable to business activity or property within a subzone, improvement subzone or expansion subzone on or before the end of the tax year, the person may claim the exemptions from income for the items set forth in section 512² for that portion of the tax year that the person was a resident or for that portion of the tax year during which the area is designated as a subzone, improvement subzone or expansion subzone.