> For a complete page index, fetch https://docs.conduit.xyz/llms.txt

# User Guide: Migrating Existing USDC Liquidity to Circle's USDC Standard

> Learn how to migrate your USDC liquidity to Circle's USDC Standard on Arbitrum chains. Step-by-step guide covering approval, withdrawal process, transaction monitoring, and bridging completion.

To migrate your existing USDC liquidity on an Arbitrum chain that has recently adopted the Bridged USDC Standard, follow the steps below.

#### Approve the USDC contract for withdrawal

Find the ERC-20 USDC contract and `approve` the 'StandardGateway' to spend the full amount of your USDC. Contact the Chain team if the address to the 'StandardGateway' was not provided.

#### Initiate withdrawal via \`outboundTransfer\`

Call the `outboundTransfer` function on the approved USDC contract with the following arguments:

* **\_l1Token**: The address of the USDC contract on the settlement layer.
* **\_to**: The address on the settlement layer where you want to withdraw the USDC.
* **\_amount**: The amount to withdraw (note: 1 USDC = `1000000` units).
* **\_data**: Leave this field empty.

#### Using Conduit Explorer

You can initiate this transaction directly through Conduit Explorer's UI, when navigating to the Standard Gateway Contract.

#### Using Foundry

Alternatively, use Foundry with the following `cast` command, replacing the placeholders with your specific details:

```bash
cast call $STANDARD_GATEWAY "outboundTransfer(address,address,uint256,uint256,uint256,bytes)" $L1_USDC_ADDRESS $YOUR_ADDRESS $AMOUNT_TO_WITHDRAW 0 0 0x --rpc-url $RPC_URL --private-key $PK
```

#### Check the withdrawal status

After processing the transaction, monitor the withdrawal status in the Superbridge UI. This interface will guide you through the proving and finalization stages.

#### Finalize the transfer on the settlement layer

Once the withdrawal is complete and your USDC is back on the settlement layer, use the Superbridge UI or other recommended bridging methods to bridge it back to your rollup.

#### Confirm bridged USDC on the rollup

Once the bridging process is complete, your USDC will appear as Bridged USDC (USDC.e) on the rollup.