How can I set up payment terms to be due on the 10th day of the following month for inv date before 25th of the current month, if after 25th would be due the month after?

Welcome to the Community, Harper.

Let me share details on setting up the invoice payment terms in QuickBooks Online (QBO).

In QBO, you can create your term by clicking the + Add new and then personalizing your term for your invoice. I suggest creating two different terms for each goal you want to achieve in your invoices: One for the net pay that will be due on the 10th day of next month and one with the terms that will be due on the 10th month of the following month. 

Here's a guide to setting a new term for your invoice:

1. Go to the Gear icon, then choose Account and Settings under Your Company.
2. Click on the Sales section.
3. From the Sales form content section, click the pencil icon to edit.
4. On the Preferred Invoice Terms drop-down, select + New.
5. Enter the name, then choose the correct option for you and enter the number of days. Once done, click Save.
6. Hit Save, once you're done configuring. 

Furthermore, you can check this article to learn more about customizing your invoice payment terms: How to Adjust Invoice Payment Terms in QuickBooks Online.

In addition, feel free to visit this helpful article and learn about personalizing sales transactions in QBO: Customize invoices, estimates, and sales receipts in QuickBooks Online.

Let me know if you have more concerns about payment periods and due dates associated with invoices in QBO. Take care and have a good one!