Thank-you for the clarification PMoore1. I hear what you're saying. Since the Service Date column isn't part of the recurring transaction template, the date that you enter will repeat for every invoice that is sent out, rather than change monthly. What you've been doing by including a message or note is what I would suggest as the most effective way to convey the details to your customers. 

I know that this is a feature that other QuickBooks users would benefit from as well, so I encourage you to submit feedback on this. Navigate to the Gear icon, then select Feedback and you can have your voice heard by our product development team. This team works hard to implement new features and improve existing ones in QuickBooks Online to best suit our customers needs. 

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