# Credits & Top-Up

Source: https://staging-docs.aiand.com/billing/credits/

ai& uses a prepaid credit model. You add credits to your organization, and inference requests deduct from that balance as they complete.

## Purchasing credits

<Steps>

1. Go to [console.aiand.com/settings/billing](https://console.aiand.com/settings/billing).
2. Click **Purchase Credits** and choose an amount.
3. Optionally apply a [Coupon](/billing/coupons/).
4. Pay via Stripe Checkout.

</Steps>

The balance is credited immediately on successful checkout. Stripe webhooks confirm the payment; if a charge later fails, the corresponding credits are reversed.

## How charges work

- Each request is billed when it completes, computed from input + output tokens.
- The cost is deducted atomically — concurrent requests can't overdraft.
- See [Pricing](/models/pricing/) for per-model rates.

## What happens at zero balance

When your balance reaches zero, new inference requests return `402 Payment Required` with a clear error. Existing in-flight requests complete and may push the balance slightly negative; the next top-up zeroes that out before adding new credit.

<Aside type="tip">
  Credits don't expire. See [Refund Policy](/billing/refunds/) for return and chargeback rules.
</Aside>