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

# Pay Gas in ERC20 Tokens

CDP Paymaster supports ERC20 token gas payments, enabling users to pay for gas in tokens like USDC instead of ETH. This eliminates the need for users to hold native tokens while still covering their own transaction costs.

## How it works

Instead of the developer sponsoring gas, the **user pays for gas in an ERC20 token**:

1. User approves the Paymaster to spend their tokens
2. User submits a transaction
3. Paymaster takes tokens from the user and pays gas in ETH
4. Transaction executes

This creates a "gasless" experience where users don't need ETH, but they still pay for their own transactions using tokens they already have.

## When to use this

| Scenario                                     | Recommended approach                                                               |
| -------------------------------------------- | ---------------------------------------------------------------------------------- |
| Developer pays all gas costs                 | [Gas Sponsorship](/paymaster/introduction/quickstart) with `useCdpPaymaster: true` |
| User pays gas, but in tokens (no ETH needed) | **ERC20 Gas Payments** (this guide)                                                |
| User pays gas in ETH                         | No Paymaster needed                                                                |

## Supported tokens

| Token | Address (Base)                               |
| ----- | -------------------------------------------- |
| USDC  | `0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913` |

Additional tokens coming soon.

## Implementation

The key requirement is ensuring the user has approved the Paymaster to spend their tokens. Include an approval in your transaction batch if the allowance is insufficient.

```javascript theme={null}
const tokenDecimals = 6;
const minTokenThreshold = 1 * 10 ** tokenDecimals; // $1
const tokenApprovalTopUp = 20 * 10 ** tokenDecimals; // $20
const tokenAddress = "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"; // USDC on Base

// CDP Paymaster contract address on Base — users must approve this address
// to allow the Paymaster to transfer tokens as payment for gas
const paymasterAddress = "0x2FAEB0760D4230Ef2aC21496Bb4F0b47D634FD4c";

// Your main transaction
const mintCall = {
  abi: nftAbi,
  functionName: "mintTo",
  to: nftContractAddress,
  args: [account.address, 1],
};

let calls = [mintCall];

// Check current allowance
const allowance = await client.readContract({
  abi: parseAbi(["function allowance(address owner, address spender) returns (uint256)"]),
  address: tokenAddress,
  functionName: "allowance",
  args: [account.address, paymasterAddress],
});

// If allowance is low, add an approval to the batch
if (allowance < minTokenThreshold) {
  calls.unshift({
    abi: parseAbi(["function approve(address spender, uint256 amount) returns (bool)"]),
    functionName: "approve",
    to: tokenAddress,
    args: [paymasterAddress, tokenApprovalTopUp],
  });
}

// Send the transaction — Paymaster handles the rest
const hash = await bundlerClient.sendUserOperation({ calls });
```

<Note>
  The approval is included in the same batch as your main transaction. This ensures the user only signs once, and the approval + transaction execute atomically.
</Note>

## Paymaster contract address

Users must approve the Paymaster contract to spend their tokens. This is the address that will transfer tokens from the user's wallet as payment for gas.

| Network      | Paymaster address                            |
| ------------ | -------------------------------------------- |
| Base Mainnet | `0x2FAEB0760D4230Ef2aC21496Bb4F0b47D634FD4c` |

<Note>
  This address is returned in the `paymasterAddress` field of error responses when approval is insufficient, so you can also discover it dynamically.
</Note>

## RPC methods

CDP Paymaster implements the following methods for ERC20 gas payments:

### pm\_getAcceptedPaymentTokens

Returns the tokens the Paymaster accepts for payment.

**Request:**

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "pm_getAcceptedPaymentTokens",
  "params": ["0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789", "0x2105", {}]
}
```

**Response:**

```json theme={null}
{
  "id": 1,
  "jsonrpc": "2.0",
  "result": {
    "acceptedTokens": [
      {
        "name": "USDC",
        "address": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913"
      }
    ]
  }
}
```

### pm\_getPaymasterData with ERC20 context

To request ERC20 payment, include the token address in the context field:

**Request:**

```json theme={null}
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "pm_getPaymasterData",
  "params": [
    { /* userOperation fields */ },
    "0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789",
    "0x2105",
    {
      "erc20": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913"
    }
  ]
}
```

**Successful response:**

The response includes a `tokenPayment` field showing the fee details:

```json theme={null}
{
  "id": 1,
  "jsonrpc": "2.0",
  "result": {
    "paymasterAndData": "0x2faeb0760d4230ef2ac21496bb4f0b47d634fd4c...",
    "tokenPayment": {
      "name": "USDC",
      "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "maxFee": "0xa7c8",
      "decimals": 6
    }
  }
}
```

**Rejection response (insufficient allowance):**

```json theme={null}
{
  "id": 1,
  "jsonrpc": "2.0",
  "error": {
    "code": -32002,
    "message": "request denied - no sponsorship and address can not pay with accepted token",
    "data": {
      "acceptedTokens": [
        {
          "name": "USDC",
          "address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"
        }
      ]
    }
  }
}
```

## Comparison: Sponsorship vs ERC20 payments

| Aspect                | Gas sponsorship               | ERC20 gas payments                |
| --------------------- | ----------------------------- | --------------------------------- |
| **Who pays**          | Developer                     | User                              |
| **Payment currency**  | Developer billed in USD       | User pays in tokens (USDC)        |
| **User needs ETH**    | No                            | No                                |
| **User needs tokens** | No                            | Yes (for payment)                 |
| **Approval required** | No                            | Yes (token approval to Paymaster) |
| **Use case**          | Onboarding, removing friction | Users cover own costs without ETH |

## Next steps

* [Gas sponsorship quickstart](/paymaster/introduction/quickstart) — Developer-paid gas
* [Paymaster FAQs](/paymaster/faqs) — Common questions
* [Base Account documentation](https://docs.base.org/base-account/guides/pay-gas-erc20) — Additional context on ERC20 gas payments