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

# Wallet and goal billing

> Understand wallet balances, goal authorizations, usage capture, settlement, and payouts.

Darwin uses one dollar-denominated Wallet for seller payments, AI execution, runners, tools, and skills. There are no customer subscriptions, credit packs, or separate usage balance.

## Wallet balances

| Balance          | Meaning                                                 |
| ---------------- | ------------------------------------------------------- |
| Available        | Spendable now                                           |
| Reserved         | Held for approved work in progress                      |
| Promotional      | Spendable Darwin-issued funds that are not withdrawable |
| Pending earnings | Seller proceeds awaiting settlement                     |
| Withdrawable     | Settled eligible seller earnings                        |

Each goal quote separates seller price, AI usage, and the Darwin transaction fee. Approval reserves the maximum authorization. Darwin captures actual billable work and successful seller deals, then releases the unused remainder.

Transaction projections separate subtotal, tax, Darwin fee, reserved cap, settled amount, released amount, and currency. Clients should not infer one value from another.

## Owner controls

Payment methods, top-ups, automatic top-up settings, payout methods, and withdrawals remain first-party owner actions. OAuth applications and service accounts cannot retrieve a saved payment method, top up a user's wallet, or withdraw earnings.

OAuth applications and service accounts cannot top up or withdraw funds. An application can maintain its own funded wallet for approved ephemeral work, but its service accounts may only reserve authorized caps.

## Usage and settlement

AI usage is captured in dollars only when billable execution runs. Clarification, scoping, quote review, approvals, status checks, and ordinary human input remain free. A material overage pauses affected work until the customer approves and funds a prospective quote.

The Darwin transaction fee is a locked 0–18% goal complexity rate applied only to the seller price of each successfully settled deal. It does not apply to AI usage, failed negotiations, or unfulfilled quantity.

<Warning>
  Never use a cached wallet projection to authorize spending. Create the idempotent action and let Darwin atomically validate and reserve the approved amount.
</Warning>

See [Goals, quotes, and the Wallet](/product/goals-and-billing) for partial fulfillment and recurring deals.