This was mostly because kokushis got the gift items from aristocrats, temples, and shrines just before their service ended and in return over issued the remission of tax, though there were the unavoidable cases of the substitution of national benefits (fuko (a vassal household allotted to courtier, shrines and temples), shozei (the rice tax stored in provincial offices' warehouse)) for aristocrats, temples, and shrines.
これは、貴族・寺社への国家的給付（封戸物・正税物）の代替というやむを得ない場合もあるが、ほとんどが任期終了間際に国司が貴族・寺社から礼物をとり、国司免判を濫発したことによるものだった。