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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.

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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.

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When to use this

ScenarioRecommended approach
Developer pays all gas costsGas Sponsorship with useCdpPaymaster: true
User pays gas, but in tokens (no ETH needed)ERC20 Gas Payments (this guide)
User pays gas in ETHNo Paymaster needed

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Supported tokens

TokenAddress (Base)
USDC0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
Additional tokens coming soon.

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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. 
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.

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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.
NetworkPaymaster address
Base Mainnet0x2FAEB0760D4230Ef2aC21496Bb4F0b47D634FD4c
This address is returned in the paymasterAddress field of error responses when approval is insufficient, so you can also discover it dynamically.

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RPC methods

CDP Paymaster implements the following methods for ERC20 gas payments:

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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"
      }
    ]
  }
}

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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"
        }
      ]
    }
  }
}

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Comparison: Sponsorship vs ERC20 payments

AspectGas sponsorshipERC20 gas payments
Who paysDeveloperUser
Payment currencyDeveloper billed in USDUser pays in tokens (USDC)
User needs ETHNoNo
User needs tokensNoYes (for payment)
Approval requiredNoYes (token approval to Paymaster)
Use caseOnboarding, removing frictionUsers cover own costs without ETH

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Next steps