The cumulative value of sales without invoices in the previous period refers to the total sales of enterprises or individuals without invoices in the previous calculation period. These sales may not be invoiced in time for various reasons, but they should still be included in the sales statistics. On the other hand, the depreciation account is used to record the depreciation of fixed assets, which accumulates the depreciation expenses of enterprises or individuals in a certain period. Therefore, when the cumulative value of sales without invoice in the previous period is equal to the cumulative total of depreciation account, it means that the two values are equal, which may be to emphasize that the amount of depreciation account is equal to the cumulative value of sales without invoice.