Proration divides an expense or income item between parties for their respective periods of responsibility. Start with a simple stated example: a three hundred dollar charge for a thirty-day period. The problem assigns ten days to the seller and twenty days to the buyer. Three hundred divided by thirty is ten dollars per day. The seller's share is one hundred dollars; the buyer's share is two hundred dollars. The allocation is only part of the closing entry. Whether the item was paid ahead or remains unpaid affects the debit and credit. Use the stated day-count basis and closing-day convention instead of assuming one universal method. Quick check: in this example, what is the seller's ten-day share? One hundred dollars. Ten days times ten dollars per day.