If you need to add late fees (e.g. for late rent payments), you can do so by adding the fee as a product within Operate. This guide will take you through the necessary steps.
Add a Product Group called Fees - Select the Product type when creating it.
Add the fee as a Product - When adding the product price, please set it to 0. In addition, uncheck Can be Zero Price at the bottom of your setup screen.
Invoice the fee along with the product/service the fee applies to - Simply create a draft invoice where you add both the product you apply the fee to and the fee product itself. When adding the fee product, adjust the price manually to the real value of the fee. (E.g. if you apply a certain percentage of the rent as a daily late payment fee, then calculate the percentage and multiply that value to the number of days the rent was late.) This is where the fact that you have unticked " Can be Zero Price" on the fee product ensures that if you ever add it to an Invoice and forget to adjust the price, Operate will notify you that it cannot be invoiced with a zero price.
Here is how an invoice that applies such a fee would look like: