A long-term care provider which is a county with a population of more than 3 million that makes intergovernmental transfer payments as provided in Section 15-3 of this Code shall be exempt from the assessment imposed by Section 5B-2 unless the exemption is adjudged to be unconstitutional or otherwise invalid, in which case the county shall pay the assessment imposed by Section 5B-2 for all assessment periods beginning on or after July 1, 1992, and the assessment so paid shall be creditable against the intergovernmental transfer payments.