If the amount computed by the county under Section 70368 is increased pursuant to this article, the county shall pay the state the difference relating back to the initial date payment was due under Section 70368. If the amount computed by the county under Section 70368 is reduced pursuant to this article, the state shall pay the county the difference relating back to the initial date payment was due under Section 70368. Upon agreement between the county and state, any amount due under this section may be made by an addition or reduction in the next scheduled county facilities payment.