Interim rule. This rule strengthens and simplifies current bidding requirements for using a single-supplier competitive system to provide a rebate for infant formulas. It also addresses new infant formula cost containment requirements which are needed due to recent changes in the infant formula industry. This rule also requires WIC State agencies to award infant formula rebate contracts based on the lowest net price, allowing the highest rebate as a basis of award only when the weighted average retail prices of the different brands of infant formula vary by 5 percent or less. A proposed rule was published July 16, 1998 and as a result of comments received we are publishing an interim rule.