(a) For a workshare discount that is equal to the cost avoided by the Postal Service for not providing the applicable service, no proposal to adjust a rate associated with that workshare discount may change the size of the discount.

(b) For a workshare discount that exceeds the cost avoided by the Postal Service for not providing the applicable service, no proposal to adjust a rate associated with that workshare discount may increase the size of the discount.

(c) For a workshare discount that is less than the cost avoided by the Postal Service for not providing the applicable service, no proposal to adjust a rate associated with that workshare discount may decrease the size of the discount.