erc20-tax-token

Minimal and gas optimized implementation of an ERC20 token with taxable swaps.

ERC20TaxSwap

ERC20TaxSwap - "Basic functionality for token that taxes swaps through a UniswapV2 pair"

Features

• Taxes are taken on swaps to any router contracts
• Taxes are accumulated in the contract until the contract balance > swapThreshold, at which point a swap to $ETH will be triggered during the next transfer or sale
• Taxes are divided into three (optional) components
  • teamFee
  • protocolFee (e.g. revenue shares)
  • liquidityFee (distributed back into the LP)
• The max the contract can swap at once is determined by the maxContractSwap variable

Deployment

A test contract is deployed on Goerli to:

0x8CD907A8502258CD7bb959B0BDEe179255B132F3

The fee breakdown is:

teamFee      = 1;
protocolFee  = 1;
liquidityFee = 1;

You can try interacting with it on Uniswap. Make sure to set slippage greater than 3%.

Configuration

A blacklist and transaction limits can be enabled in the constructor with limitsActive and blacklistActive arguments. Furthermore, various configuration parameters have been set to reasonable values, but can be updated (warning: misconfiguring these variables can cause problems):

// The balance at which the contract attempts to swap to ETH
swapThreshold = initialSupply.mulDiv(5, 10000); // 0.05%

// The max that can be swapped at once
maxContractSwap = initialSupply.mulDiv(50, 10000); // 0.5%

// If limits are active, the max size of a buy or sell
maxTransaction = initialSupply.mulDiv(100, 10000); // 1%

// If limits are active, the max wallet size
maxWallet = initialSupply.mulDiv(100, 10000); // 1%

Minting

By default, the initialSupply is minted in the constructor and the token is no longer mintable. To change this, you would need write a new function utilizing the ERC20 _mint(address to, uint amount) function.

Note: It's recommended to keep initialSupply as a hard cap and base the mint schedule around this hard cap. This way parameters like swapThreshold can be based around the initialSupply, whereas a tax token with a completely unpredictable supply would be hard to configure.

Testing

Add a .env file with a valid RPC endpoint as indicated in .env.example:

MAINNET_RPC_URL = https://mainnet.infura.io/v3/XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Then run:

forge install
npm install
npm run build
npm run test

Note: the RPC endpoint must be Mainnet Ethereum (or Goerli), otherwise the V2 router address needs to be updated.

Safety

This is experimental software and is provided on an "as is" and "as available" basis.