erc20-tax-token

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

Contracts

tokens
├─ ERC20SwapTax — "Optimized and fully featured ERC20 with taxes token swaps"
├─ ERC20SwapTaxMintable — "Mintable ERC20SwapTax implementation"

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

Installation

To install with Foundry:

forge install moodycoins/erc20-tax-token

To install with Hardhat or Truffle:

npm install erc20-tax-token

Try It

A test contract is deployed on Goerli to:

0x12308bCA3fadFBe6c8154d591cDfE5Df96eAB4Bb

The fee breakdown is:

teamFee      = 1; // 1%
protocolFee  = 1; // 1%
liquidityFee = 1; // 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

Use the extension contract ERC20SwapTaxMintable.sol which exposes the mintTo() function. You can choose whether or not to set a maxSupply in the constructor, which will put a hard-cap on minting.

Note: Changing the totalSupply by large amounts can result in variables like swapThreshold becoming invalid. Be sure the keep this in mind!

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.