Can you apply a payment plan to multiple invoices?

Short answer is currently no, but this feature may come in future updates. For now each invoice will need to be enrolled into a seperate plan, or you can do you own invoice consolidation if recommended by an accountant.

If you have a customer who has multiple invoices that all need to go onto a payment plan, you will need to add each invoice to a specific payment plan. You can do this by creating a Breakdown an Existing Invoice payment plan, and then applying it manually to each invoice by navigating to the invoice page via the corresponding customer details page. You can find the customer's customer details page by searching on this page.

We are aware that this process is not perfect and creating a better way to offer payment plans to customers who have multiple invoices is one of our priority new features so you can expect to hear about it in the not too distant future.