Invoices for same amount each month with occasional extras

You can memorize the customer invoices to auto-post or just remind you to post and then edit the invoice to add the extras. Or you can just each month copy the last one and make current changes.

I set mine to Automatic in the Memorized Transactions List. Then, after they are created by QB, I review and Update to refine them with any changes or additional charges for that customer for that month. This is why I set them to Last date of the month, but to be generated 10 days early. That gives me time to update them and still get them into the mail around the 25th.