The unit is a completed subject
Each successfully completed production screen counts one subject, whether the outcome is potential_match or no_match. Each completed batch row counts separately. Each completed monitoring rescreen counts again because it is a new check. HTTP requests, source count, and number of potential matches do not directly define the billable unit.
Idempotent retries do not count twice. Failed rows and failed screening attempts do not count as completed screens. A fresh request with a new idempotency key is a new screen, even if the same subject was screened before. A cached idempotent response is the original operation, not new usage.
Read used, reserved, and remaining together
GET /api/v1/usage returns the environment, period, used and reserved quantities, allowance, remaining quantity, plan, and usage by kind. Reserved quantity represents accepted work that has not yet completed. Cancellation or row failures release unused reservations.
Production periods follow the subscription billing period; sandbox periods follow calendar months. Sandbox activity is separate and never billed. The settings field spendingCap currently means a maximum subject count, not a dollar-denominated overage budget; zero uses the plan allowance. There are no automatic overages.
Budget monitoring explicitly
One daily monitor can use roughly 30 subjects in a 30-day period before source-update rescreens. Multiplying the monitor-count limit by the daily schedule can exceed a plan’s screening allowance. Choose the number of retained monitors with expected update volume and interactive traffic in mind. If the cap is reached, screening is blocked without creating extra charges.
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