Co-term webhooks notify your system of events across the subscription group lifecycle and billing process. They provide data on actions such as co-term group creation, proration adjustments, billing charge completions, and co-term group deactivation.

By monitoring these webhooks, your system can automate billing operations, update records, trigger notifications, and manage dunning workflows in real-time.

Prerequisites

Before you can receive co-term-related webhook events, you have to initiate the co-term webhooks. To initiate co-term webhooks, follow the steps below:

Create a co-term group:
```
POST /subscriptions/coterm
```
Start by grouping the relevant subscriptions together using the create a new co-term group API endpoint.
Generate a co-term group estimate:
```
POST /subscriptions/coterm/`{cotermGroupId}`/estimate
```
Calculate any proration or adjustments for the grouped subscriptions using the generate a co-term group estimate API endpoint. This step provides an estimate of the changes that will be applied.
Execute the co-term group:
```
POST /subscriptions/coterm/`{cotermGroupId}`/execute
```
Finalize the process by calling the execute a co-term group API endpoint. This step performs the following actions:
- The system applies the calculated adjustments.
- The following webhook events are triggered simultaneously:
  - subscription.group.created
  - subscription.group.prorated
- The system updates the renewal date for the co-term group.
- The customer is charged the prorated amount.

Co-term webhook events

The table below provides an overview of all co-term webhook events and their trigger conditions:

Event Name	Trigger Condition
subscription.group.created / subscription.group.prorated	Triggered after co-term initiation steps are completed (group creation, estimation, and execution). The customer is charged for prorated adjustments.
subscription.group.payment.charge.completed	Sent at renewal when the charge (rebill) succeeds for the grouped subscription.
subscription.group.updated	Sent when a new subscription is added to an existing co-term group.
subscription.group.payment.reminder	(Optional) Sent at the scheduled reminder time for the most recent purchase.
subscription.group.payment.charge.failed	Sent when the grouped rebill fails and the co-term group enters dunning.
subscription.group.payment.overdue	(Optional) Sent when a payment becomes overdue based on the purchase schedule.
subscription.group.deactivated	Sent after the dunning period ends, when subscriptions in the co-term group are deactivated.