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# Burn Blocked Tokens \[token.burnBlocked]

Burns TIP-20 tokens from a blocked address. Requires the `BURN_BLOCKED` role. [Learn more about token roles](https://docs.tempo.xyz/protocol/tip403/spec)

## Usage

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

const { receipt } = await client.token.burnBlockedSync({
  amount: { formatted: '10.5' },
  from: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb',
  token: '0x20c0000000000000000000000000000000000000',
})

console.log('Transaction hash:', receipt.transactionHash)
// @log: Transaction hash: 0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/tempo/viem.config.ts:setup]
```
:::

### Undeclared Tokens

Formatted amounts resolve `decimals` from the Client's declared `tokens` (the pathUSD address above is declared on the default token set). For a token not declared on the Client, include `amount.decimals` so the formatted amount can be parsed.

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

const { receipt } = await client.token.burnBlockedSync({
  amount: { decimals: 6, formatted: '10.5' },
  from: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb',
  token: '0x20c0000000000000000000000000000000000001',
})
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/tempo/viem.config.ts:setup]
```
:::

### Base Amounts

Pass a `bigint` to use the token's base unit amount directly.

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

const { receipt } = await client.token.burnBlockedSync({
  amount: 10500000n,
  from: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb',
  token: '0x20c0000000000000000000000000000000000000',
})
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/tempo/viem.config.ts:setup]
```
:::

### Asynchronous Usage

The examples above use a `*Sync` variant of the action, that will wait for the transaction to be included before returning.

If you are optimizing for performance, you should use the non-sync `token.burnBlocked` action and wait for inclusion manually:

```ts twoslash
import { Actions } from 'viem/tempo'
import { client } from './viem.config'

const hash = await client.token.burnBlocked({
  amount: { formatted: '10.5' },
  from: '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb',
  token: '0x20c0000000000000000000000000000000000000',
})
const receipt = await client.transaction.waitForReceipt({ hash }).receipt

const { args } = Actions.token.burnBlocked.extractEvent(receipt.logs)
```

## Recipes

### Confirm an Address Is Blocked Before Burning

Check the address against your transfer policy with [`policy.isAuthorized`](/tempo/actions/policy.isAuthorized) first: the burn is irreversible, so only proceed when the policy still blocks the holder.

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

const from = '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb'
const token = '0x20c0000000000000000000000000000000000000'

const isAuthorized = await client.policy.isAuthorized({ // [!code focus]
  policyId: 1n, // [!code focus]
  user: from, // [!code focus]
}) // [!code focus]
if (isAuthorized) throw new Error('address is not blocked by the policy') // [!code focus]

const { receipt } = await client.token.burnBlockedSync({
  amount: { formatted: '10.5' },
  from,
  token,
})
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/tempo/viem.config.ts:setup]
```
:::

### Burn a Blocked Account's Entire Balance

Combine [`token.getBalance`](/tempo/actions/token.getBalance) with `token.burnBlockedSync` to clear a sanctioned account completely, for example when executing a documented seizure order.

:::code-group
```ts twoslash [example.ts]
import { client } from './viem.config'

const from = '0x742d35Cc6634C0532925a3b844Bc9e7595f0bEbb'
const token = '0x20c0000000000000000000000000000000000000'

const { amount } = await client.token.getBalance({ account: from, token }) // [!code focus]

const { receipt } = await client.token.burnBlockedSync({
  amount, // [!code focus]
  from,
  token,
})
```

```ts twoslash [viem.config.ts] filename="viem.config.ts"
// [!include ~/snippets/tempo/viem.config.ts:setup]
```
:::

## Return Value

```ts
type ReturnType = {
  /** Address tokens were burned from. */
  from: Address
  /** Burned amount, in base units. */
  amount: bigint
  /** Token decimals used to derive `formatted`, if known. */
  decimals?: number | undefined
  /** Burned amount formatted with the token's `decimals`, if known. */
  formatted?: string | undefined
  /** Transaction receipt. */
  receipt: TransactionReceipt
}
```

## Parameters

### amount

* **Type:** `bigint | { decimals?: number, formatted: string }`

Amount of tokens to burn, in base units or formatted decimal form. Include `amount.decimals`
when the token is not declared on the Client's `tokens`.

### from

* **Type:** `Address`

Address to burn tokens from.

### token

* **Type:** `Address | bigint`

Token to operate on: a TIP-20 token id or a contract address.

### account (optional)

* **Type:** `Account | Address`

Account that will be used to send the transaction.

### feePayer (optional)

* **Type:** `Account | boolean`

Fee payer for the transaction (TIP-1 gas sponsorship).

Pass `true` to defer the fee token to an external fee payer (e.g. a relay), or a local Account to co-sign the transaction as the fee payer.

### feeToken (optional)

* **Type:** `Address | bigint`

Fee token for the transaction.

Can be an unpaused USD-denominated TIP-20 token address or ID.

### gas (optional)

* **Type:** `bigint`

Gas limit for the transaction.

### keyAuthorization (optional)

* **Type:** `KeyAuthorization`

Signed key authorization to include with the transaction, authorizing an access key to act for the sending account.

### maxFeePerGas (optional)

* **Type:** `bigint`

Max fee per gas for the transaction.

### maxPriorityFeePerGas (optional)

* **Type:** `bigint`

Max priority fee per gas for the transaction.

### nonce (optional)

* **Type:** `number`

Nonce for the transaction.

### nonceKey (optional)

* **Type:** `'expiring' | 'random' | bigint`

Nonce key for the transaction (TIP-1009 2D nonces).

Use `'expiring'` to select an expiring nonce, which enables concurrent transaction submission without nonce ordering. Use `'random'` to select a random key.

### throwOnReceiptRevert (optional)

* **Type:** `boolean`
* **Default:** `true`

Whether a `Sync` action throws when the receipt reports a revert.

### validAfter (optional)

* **Type:** `number`

Unix timestamp after which the transaction can be included.

### validBefore (optional)

* **Type:** `number`

Unix timestamp before which the transaction must be included.