# Billing and credits

Use this document when reasoning about who pays, how spend is limited, or whether a failed operation is charged.

## Account model

| Object | Billing behavior |
|---|---|
| Organization | Owns one shared credit balance. |
| Agent | Spends from its organization and receives attribution. |
| Project key | Spends from one grant and receives independent attribution and revocation. |
| User | Acts through organizations; there is no separate per-user wallet. |

Every user receives a personal organization at signup. Team organizations use the same model.

## Charge lifecycle

1. Core verifies the exact capability definition.
2. The spend kernel authorizes a maximum amount.
3. The operation runs.
4. Success captures observed cost, capped by the authorization.
5. Failure voids the authorization and charges `$0.00`.

Spend limits are deterministic. An AI model cannot waive them. An unavailable billing service returns a service error; it must not be interpreted as insufficient credits.

## Manage spend

Use [Build account settings](https://build.core.so/account) to view balance, add credits, inspect receipts, and manage limits. Use separate project keys when attribution or revocation must be isolated.

## Related

- [Model router and project keys](https://docs.core.so/api-keys-and-inference.md)
- [Account access](https://docs.core.so/mcp-account-access.md)