I am running into many clients not paying. How can I charge interest on my invoices when they are overdue?

It's awesome to have you here in the community, @beth-vivacacao-c.

I can share your options to add interest to your overdue invoices. This process has to be done manually as there isn't currently a feature to add automatic interests to unpaid entries.

First, you'll need to create a service or non-inventory item for the interest and process the interest by:

• creating a separate invoice for the charge
• adding another line item on the past due invoice

Here are the steps to add the interest item:

1. Click the Gear icon, then choose Products and Services.
2. Press New.
3. Choose either Non-inventory or Service.
   
4. Enter a desired name of the interest.
5. Select an Income account, then click Save and close.
   

Now, here's how you can add the item on the new invoice:

1. Click the New (+) icon, then choose Invoice.
2. Under the PRODUCT/SERVICE column, add the interest item.
3. Enter the amount manually in the AMOUNT tab.
4. Press Save and close.

If you want to include the interest on the existing invoice, here's how:

1. Press Sales, then go to the Customers tab.
2. Choose the customer, then look for the past due invoice.
3. Add the interest item in the unused line, then enter the amount.
   
4. Click Save and close.

Here's a helpful article for sending invoice reminders in QuickBooks Online.

Please visit this thread again if you need further assistance with the interest application. I'll be right here to help you out. All the best!