Change subscription quantity in potential invoice

What does this do? Sets a custom quantity for a subscription billing row in a potential invoice. For per-unit pricing subscriptions, this allows you to adjust how many units are billed, which may differ from the default quantity calculated by the system.

When to use:

• To adjust the quantity for per-unit pricing subscriptions before finalizing the invoice
• To bill a different number of units than the default calculated amount
• To correct billing quantities based on actual usage or customer agreements
• To clear a custom quantity and revert to the default calculated quantity

How it works:

• Updates the subscription quantity stored in the potential invoice metadata
• The quantity is used to calculate the total charge (quantity × unit price)
• Setting value to null or omitting it clears the custom quantity and reverts to default
• The quantity must be a non-negative integer
• Only affects the current potential invoice; does not modify the subscription billing configuration

Subscription requirements:

• Subscription billing ID (itemId) must exist in the potential invoice
• Use the billingId field from subscription billing rows
• Only per-unit pricing subscriptions (payment type: perUnit) typically use quantities
• Fixed monthly fees and one-time charges may not use quantities

Invoice ID Format: The invoice ID follows the format: {type}::{projectId}::{dateFrom}::{dateTo}

• Example: SingleProject::0e9d033a-ab41-4212-8637-66c4e3b01fe2::2025-10-01::2025-10-31

Permission requirements: Requires Invoices.manage permission and access to the project.

curl -X POST "https://leadtime.app/api/public/billing/potential-invoices/SingleProject%3A%3A0e9d033a-ab41-4212-8637-66c4e3b01fe2%3A%3A2025-10-01%3A%3A2025-10-31/subscriptions/550e8400-e29b-41d4-a716-446655440000/quantity" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
  "value": 5
}'

const response = await fetch("https://leadtime.app/api/public/billing/potential-invoices/SingleProject%3A%3A0e9d033a-ab41-4212-8637-66c4e3b01fe2%3A%3A2025-10-01%3A%3A2025-10-31/subscriptions/550e8400-e29b-41d4-a716-446655440000/quantity", {
  method: "POST",
  headers: {
    "Authorization": "Bearer YOUR_ACCESS_TOKEN",
    "Content-Type": "application/json"
  },
  body: "{\n  \"value\": 5\n}"
});

import requests

response = requests.post(
    "https://leadtime.app/api/public/billing/potential-invoices/SingleProject%3A%3A0e9d033a-ab41-4212-8637-66c4e3b01fe2%3A%3A2025-10-01%3A%3A2025-10-31/subscriptions/550e8400-e29b-41d4-a716-446655440000/quantity",
    headers={
        "Authorization": "Bearer YOUR_ACCESS_TOKEN",
        "Content-Type": "application/json"
    },
    data="{\n  \"value\": 5\n}",
)

{
  "success": true
}