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

# ASA Opt-In Precheck

> A doomed-to-fail settlement should be caught at /verify, not burn a real on-chain fee at /settle.

<CardGroup cols={4}>
  <Card title="Invariant" icon="tag">A2</Card>
  <Card title="Category" icon="link">Algorand</Card>
  <Card title="Priority" icon="circle-dashed">Stretch</Card>
  <Card title="Violation class" icon="triangle-exclamation">Service Denial (efficiency)</Card>
</CardGroup>

## What it proves

Algorand requires an account to explicitly **opt in** before it can receive a given Algorand
Standard Asset (ASA) — a transfer to a non-opted-in account fails on-chain. A facilitator that only
discovers this at broadcast time burns a real transaction fee settling a payment that was always
going to fail. A2 asserts the facilitator catches this earlier, at `/verify` time.

**Source:** Algorand ASA opt-in requirement (protocol primitive); early detection vs. wasted
on-chain fees.

## How it works

<Steps>
  <Step title="Generate a fresh account">
    A brand-new keypair that has never opted into the test ASA (TestNet USDC) is confirmed
    not opted in via a direct account-info lookup.
  </Step>

  <Step title="Build a payment targeting it">
    A normal, correctly-signed payment from the funded client account to this never-opted-in
    address.
  </Step>

  <Step title="Call /verify">
    A facilitator whose `/verify` step runs a full algod simulation (`simulateTransactionGroup` —
    see [D7](/reference/decision-log#d7-ground-truth-pulled-from-the-installed-package-source-not-just-docs))
    catches the doomed transfer before any real settlement attempt.
  </Step>
</Steps>

## Pass condition

```ts theme={null}
const passed = !optedIn && caughtEarly;
```

Both the generated account's opt-in status must genuinely be `false` (otherwise the sub-case
didn't test the intended condition at all — reported distinctly rather than silently passing), and
`/verify` must reject the payment.

## Reading a failure

If `/verify` approves a payment to a non-opted-in recipient, the facilitator would burn a real fee
discovering the failure only at `/settle` — reported as *"verify APPROVED a payment to a
non-opted-in recipient — this would fail on-chain and waste a real settlement attempt."*

<Card title="Next: Rekey Authorization" icon="key" href="/invariants/a3-rekey-authorization" horizontal />