The after a primary invoice installment is paid trigger lets you run actions based on a client paying a single installment in a payment plan — for example, holding off on delivering files the deposit is paid. It's a powerful capability, but pairing payment plans with flows has a few rules you'll want to follow to avoid errors.
This article covers an advanced technique. Before proceeding, make sure you're comfortable working with flows, payment plans, invoices, and proposals.
Setting up the payment plan on your flow template
Before you can use the installment-paid trigger, you need to attach a payment plan to your flow template. This connection is what makes the trigger available — and it's set on the template itself, not on an individual project.
The Payment Plan selector appears only when editing a flow template. If you're looking at a flow already applied to a project, the selector won't be there. Set the payment plan on the template before you apply it.
To attach a payment plan to a flow template:
Navigate to Flows ➔ Flow Templates in the main sidebar.
Click the template you want to configure.
Click the Edit button (pencil icon) to open the flow editor.
In the flow editor header, click the Payment Plan selector and choose the payment plan you want to attach.
Click Save to confirm.
Once a payment plan is attached, the after a primary invoice installment is paid trigger (under the Primary Invoice trigger category) becomes available when building out your trigger steps. When configuring that trigger, you'll use the Installment to watch field to pick the specific installment that should fire the trigger.
If you only need to react when the client pays off the full invoice, you don't need a payment plan at all. Use the after the primary invoice is paid in full trigger instead (also under Primary Invoice) and leave the Payment Plan selector empty.
How flows with payment plans create invoices
When you apply a flow to a project, a flow with a payment plan automatically creates a $0.00 primary invoice and attaches the payment plan to it. The flow then watches that invoice for installment payments.
If the project already has a primary invoice when you apply the flow, the flow's payment plan is applied to (and replaces the payment plan on) that existing invoice. Test thoroughly when applying flows to projects that already have invoices in progress.
There are two ways to add line items to the flow-created invoice:
Through a proposal in the flow — When a client selects packages from a proposal that's part of the flow, those packages land directly on the flow-created invoice.
Manually — Open the primary invoice in the project and add line items or packages yourself.
Rules for working with payment plans and flows
The installment-paid trigger relies on a specific relationship between the flow, its invoice, and its payment plan. Several common setups can break that relationship. The sections below cover each one.
Leave the payment plan blank on proposals used with the flow
If you're sending a proposal through a flow that has a payment plan — or using a public proposal to start that flow — the proposal itself must not have its own payment plan selected. If it does, the proposal's plan conflicts with the flow's plan and breaks the installment trigger.
In the proposal's settings, the Payment plan field must be left empty. You can confirm this by opening the proposal template in the form builder and checking that no payment plan is selected.
Even attaching the exact same payment plan to both the proposal and the flow will cause an error. The fix is always to clear the payment plan from the proposal.
The Create Invoice action won't work with the installment trigger
The flow's installment trigger watches the primary invoice — the one the flow created when it was applied. If your flow setup produces a second invoice at any point, the trigger won't fire on that second invoice's installments.
The Create Invoice action always creates a separate invoice. It has its own Payment Plan selector, but applying a plan there doesn't change what the flow watches — the flow still monitors the primary invoice only.
Setups that work with the installment trigger:
Sending a proposal with required packages through the flow (packages land on the primary invoice)
Manually adding line items to the primary invoice
Setting a flow with a payment plan as the default flow on a public proposal
Setting a flow with a payment plan as the default flow on a public proposal that's attached to a scheduler (with or without a required deposit on the scheduler)
Setups that create an extra invoice and won't work:
Using the Create Invoice action in the flow
Sending a scheduler with an attached proposal or required deposit through the flow
Starting the flow from a lead capture attached to a scheduler with a required deposit
If you're not sure whether your setup works, the best way to confirm is to test it.
Don't remove or replace the payment plan on the flow-created invoice
After the flow creates an invoice with a payment plan attached, you can edit individual installments — adjusting amounts, due dates, or reminders is fine. What you should not do is delete installments or swap the payment plan for a different one. Either action breaks the installment trigger.
For more on how autopay interacts with payment plans, see autopay on payment plans.
A flow accepts only one payment plan
Each flow template can have only one payment plan attached. If you offer multiple payment structures, create a separate flow template for each one.
A second flow with a payment plan overrides the first
If you apply a second flow with a payment plan to a project that already has a flow with a payment plan, the second flow's plan replaces the first. The first flow's installment trigger will stop watching correctly.
To avoid this when working with phased flows, specify the payment plan only on the flow where the invoice is first needed — typically the flow where the proposal is sent. Leave the Payment Plan selector empty on any follow-up flows applied to the same project. Errors are less likely when the earlier flow's actions have all finished before the next flow is applied, so testing each phase is worth the time.
FAQ
How do I test my flow?
Apply the flow to a project where you're the client, then confirm that the invoice looks right and the flow shows no errors. To fire payment-related triggers without waiting for a real payment, manually log a payment on the invoice to the appropriate installment amount.
What if there's already a primary invoice on the project when I apply a flow with a payment plan?
The flow applies its payment plan to the existing primary invoice, replacing any payment plan that was already there. Make sure you've tested this scenario if your projects typically have invoices before a flow is applied.
I set the exact same payment plan on my proposal and my flow. Why am I still getting an error?
The proposal's payment plan always takes precedence on the backend, which breaks the installment trigger even when the plans are identical. Clear the payment plan from the proposal — leaving it empty is the only fix.
If I choose a payment plan inside the Create Invoice action, will the installment trigger work?
No. Selecting a payment plan inside the Create Invoice action applies that plan to the extra invoice the action creates, not the primary invoice. The flow's installment trigger only watches the primary invoice, so it won't fire based on the extra invoice's installments.