Payments by certain nonprofit organizations
A State may, without being deemed to violate the standards set forth in subsection (a), permit an organization (or a group of organizations) described in section 501(c)(3) which is exempt from income tax under section 501(a) to elect (in lieu of paying contributions) to pay into the State unemployment fund amounts equal to the amounts of compensation attributable under the State law to service performed in the employ of such organization (or group).