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:

User approves the Paymaster to spend their tokens
User submits a transaction
Paymaster takes tokens from the user and pays gas in ETH
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 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.

import { parseAbi } from 'viem';

// Replace these with your own app's values:
// const nftAbi = [...];
// const nftContractAddress = "0x...";
// const account = ...; // your smart account
// const client = ...; // viem PublicClient
// const bundlerClient = ...; // your bundler client

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 });

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.

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`

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

RPC methods

CDP Paymaster implements the following methods for ERC20 gas payments:

pm_getAcceptedPaymentTokens

Returns the tokens the Paymaster accepts for payment. Request:

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "pm_getAcceptedPaymentTokens",
  "params": ["0x5FF137D4b0FDCD49DcA30c7CF57E578a026d2789", "0x2105", {}]
}

Response:

{
  "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:

{
  "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:

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

Rejection response (insufficient allowance):

{
  "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 — Developer-paid gas
Paymaster FAQs — Common questions
Base Account documentation — Additional context on ERC20 gas payments

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How it works

When to use this

Supported tokens

Implementation

Paymaster contract address

RPC methods

pm_getAcceptedPaymentTokens

pm_getPaymasterData with ERC20 context

Comparison: Sponsorship vs ERC20 payments

Next steps

​How it works

​When to use this

​Supported tokens

​Implementation

​Paymaster contract address

​RPC methods

​pm_getAcceptedPaymentTokens

​pm_getPaymasterData with ERC20 context

​Comparison: Sponsorship vs ERC20 payments

​Next steps

How it works

When to use this

Supported tokens

Implementation

Paymaster contract address

RPC methods

pm_getAcceptedPaymentTokens

pm_getPaymasterData with ERC20 context

Comparison: Sponsorship vs ERC20 payments

Next steps