Customer invoice with summary by category at the end of the invoice

Doesn't seem like there is an option for that. However, you try this:

Use "Add Subtotal" to add subtotal after each group of invoice lines and also customize invoice template to add subgroup totals.

I can see the convenience of having a summary by category details on your customer invoices, SAHarris1. Let me share input regarding this matter.

In QuickBooks, there isn't a direct way to add a summary by category at the end of your customer invoices. However, we can consider following the insights shared by @Accracy Accounting above as a workaround. This way, subtotals of each item line group on your invoices are summarized into one.

To do this:

1. In your QuickBooks Online account, click the +New icon and select Invoices.
2. Enter your customer's details, product and service items and amounts.
3. Under the Add product or service dropdown, select Add Subtotal.
4. You can enter another item, then repeat adding subtotals of each group.
5. Review all information. Then, click Save and Close.

Additionally, you can make specific customizations or include an account summary in your customer sales forms.

Once everything comes in handy in the future, you can receive and track customer-paid invoices to ensure accurate recording of your sales transactions.

I'll always be available in this forum if there's anything else you need further assistance with when managing customer invoices in your account. Keep safe and have a great day ahead!