> ## Documentation Index
> Fetch the complete documentation index at: https://docs.tamradar.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Update-Based Billing

> Update-based billing flow, insufficient-funds behavior, and auto-reactivation.

Update-based radars are charged only when TAMradar produces approved updates.

## Billing Mechanics

* No charge happens at creation.
* `next_charge_at` is `null`.
* Balance is deducted per approved finding.

## Deactivation and Reactivation

* If balance reaches zero, the radar transitions to `inactive`.
* When balance is topped up, affected update-based radars can auto-reactivate.
* User-triggered deactivation sets the radar to `inactive` immediately (no grace period).

## Failure and Refund Behavior

* Setup failures still emit `radar_failure` webhooks.
* For update-based setup failures, `refund_amount_usd` is typically `0` because no creation charge was taken.
* Failure `code` is `400` for setup failures (`missing_prerequisites`, `source_inaccessible`, `setup_failure`) and `402` for insufficient funds. See `message` for details.

## What to Monitor

* `balance_remaining_usd` from `GET /v1/account`.
* `radar_failure` events for funding and setup issues.
* Bulk workflows (`POST /v1/radars/bulk` + `GET /v1/radars/bulk/{bulk_id}`) for async item-level failures.