This is especially confusing to small business owners who use their accounting software in brief sit-downs consisting of just a few tasks at a time. Then, when all bills are entered, the user is expected to pay the bill in the “Pay Bills” window. QuickBooks for Mac Inventory: input errorsĮnjoy! The top 4 most common Quickbooks input errors: Writing a check AFTER you enter a bill QuickBooks is designed with the expectation that you will enter each bill as it arrives using the “Enter Bills” window.