This event fires when your available (free) balance crosses below the threshold you configured for the workspace, so you can top up before sends fail.

​
Payload

{
  "id": "evt_xxxxx",
  "event": "billing.balance_low",
  "timestamp": "2026-03-28T09:00:00Z",
  "data": {
    "balance": {
      "free": 4.82,
      "reserved": 1.18,
      "total": 6.00
    },
    "threshold": 5.00,
    "currency": "EUR"
  }
}
​
data.balance.free
number
Available balance after all active holds.
​
data.balance.reserved
number
Balance held for in-flight messages not yet settled.
​
data.threshold
number
The configured low-balance threshold that triggered this alert.