Retainer Billing with Variable Amounts
Charge retainer clients based on actual work delivered
Goal: Bill retainer clients a variable amount each month based on hours worked or services delivered. The amount changes each cycle, the billing infrastructure stays the same.
What You'll Need
Steps
Create a retainer item
Edge > Billable Items > New Item. Trigger type. Mode: Variable, Capture: Charge Immediately, Condition: >=, Threshold: 1 (any hours), Price: $2,000 (default), Allow Override: Yes, Max Capture: $15,000.
Set up the client
Create billing customer with payment method and trigger permissions.
Enroll the client
Enroll in the retainer item. Stays active month after month.
Calculate monthly amount
At end of each billing cycle, calculate: hours worked x hourly rate. Example: 47 hours x $150/hr = $7,050.
Fire with the amount
Call the fire endpoint:
`POST /apis/edge/trigger/fire.php`
`{"billable_item_id": "bi_xxx", "billing_customer_id": "bc_xxx", "override_amount": 7050.00}`
Or click Charge Now and enter $7,050. Edge charges immediately.
Automate with a cron or Flow
Set up a scheduled job that calculates each client's amount and fires the trigger via API monthly. Removes the manual step.
Result
Each cycle, the retainer client is charged the exact amount for work delivered. The amount varies, the billing process does not.
Variations
Client-confirmed retainer
Use client_confirm instead. Client receives monthly invoice with hours breakdown and approves. More oversight.
Minimum retainer with overage
Set bi_unit_price to minimum (e.g., $2,000). Only pass override_amount when actual exceeds minimum.
