Perpetual FIFO

Under the perpetual system the Inventory account is constantly (or perpetually) changing. When a retailer purchases merchandise, the retailer debits its Inventory account for the cost; when the retailer sells the merchandise to its customers its Inventory account is credited and its Cost of Goods Sold account is debited for the cost of the goods sold. Rather than staying dormant as it does with the periodic method, the Inventory account balance is continuously updated.

Under the perpetual system, two transactions are recorded when merchandise is sold: (1) the sales amount is debited to Accounts Receivable or Cash and is credited to Sales, and (2) the cost of the merchandise sold is debited to Cost of Goods Sold and is credited to Inventory. (Note: Under the periodic system the second entry is not made.)

With perpetual FIFO, the first (or oldest) costs are the first moved from the Inventory account and debited to the Cost of Goods Sold account. The end result under perpetual FIFO is the same as under periodic FIFO. In other words, the first costs are the same whether you move the cost out of inventory with each sale (perpetual) or whether you wait until the year is over (periodic).