Debiting an expense account is a bookkeeping transaction that records the use of funds for expenses incurred. The process involves subtracting (debiting) the cost from an asset or liability account and adding (crediting) it to an expense account. In other words, when you debit an expense account, you are recording that an expense has been made in the bookkeeping system. This helps to track where money is being used within your business so you can manage your spending and profitability more effectively.