Minimum bonus carry-forward governs deficiency set-off when allocable surplus is unavailable or insufficient for payment. Minimum bonus not payable in full for an accounting year where there is no available surplus, or where the allocable surplus is insufficient, and no adequate amount has been carried forward and set on under the preceding rule. The minimum amount due, or the deficiency in that amount, is carried forward for set-off in the succeeding accounting year and subsequent years, up to and including the fourth accounting year, in accordance with the prescribed illustration.