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

# Check & Deduct Credits

Atomically check if a customer has sufficient credit balance and deduct in a single database transaction. Uses row-level locking to prevent race conditions under concurrent requests.

**Auth:** `sk_` only

<ParamField body="customer_id" type="string" required>
  External customer ID
</ParamField>

<ParamField body="feature" type="string" required>
  Feature being consumed
</ParamField>

<ParamField body="credits" type="number" required>
  Number of credits to deduct (must be positive)
</ParamField>

<ResponseField name="allowed" type="boolean" required>
  Whether sufficient balance existed to fulfill the deduction
</ResponseField>

<ResponseField name="remaining" type="number" required>
  Credit balance after deduction (or unchanged balance if denied)
</ResponseField>

<Note>
  When `allowed` is `false`, no credits are deducted. The `remaining` field returns the current balance as-is.
</Note>