Reuse an ERC-20 approval when you trade the same token through the same trusted exchange contract on Base. An approval is permission for a contract to move a set amount of your tokens; checking it before each trade can save an extra transaction. Keep the amount limited if you want to reduce what that contract could take.
- An approval is tied to a token, a contract, and a network.
- A trade can use an existing allowance only if enough remains.
- A larger allowance saves repeat approvals but gives broader permission.
Approvals save a transaction when the allowance still covers the trade
An ERC-20 token is a common format for tradeable tokens, and its approval lets another address spend them for you. For a decentralized exchange, that address is often a router: a blockchain program that handles token trades or liquidity deposits.
Think of an approval like a prepaid spending limit at one shop. A $100 limit can cover several smaller purchases there, but it does not work at another shop. On Base, the permission belongs to a specific token and contract address on that network.
Check the token, contract, network, and remaining amount
Before relying on an old approval, verify that it matches the action you plan to take. Follow these steps before your next trade.
- Confirm the network. Make sure your wallet is using Base, Coinbase’s Ethereum layer 2, a network that processes transactions alongside Ethereum. An approval on another network does not carry over.
- Identify the token and spender. Check which token is being spent and which contract receives permission. A different token or contract needs its own approval.
- Read the remaining allowance. Allowance means the amount the contract can still spend. Compare it with the amount you plan to trade. For example, if you approved 100 USDC and spent 40, a standard token may leave 60 available.
- Choose the amount for any new approval. Approving 100 USDC can cover repeated trades until that allowance runs low. An unlimited approval can avoid repeat approvals, but it lets that contract spend your token balance up to the token’s rules.
- Review and confirm the transaction. An approval is a separate on-chain transaction, meaning it is recorded on Base, and it uses gas: the network fee paid in ETH. A later trade also uses gas, so reusing a valid allowance can save one transaction and its fee.
Use limited approvals when the savings do not justify broad access
For frequent trades through the same contract, a larger allowance can mean fewer interruptions. For a new or rarely used contract, approving only the planned amount limits what it can spend if you stop using it.
Allowances can behave differently across tokens. Some reduce the remaining amount as tokens are spent; others may treat a very large allowance as effectively unlimited. If an approval change fails, the ERC-20 standard’s guidance is to set the allowance to zero before setting a new amount. That can require another transaction and fee.
The EIP-20 standard defines token approvals, while Base’s documentation explains that Base transactions use ETH for gas. Use those basics to judge the trade-off: fewer approval transactions can save time and fees, while smaller allowances reduce exposure.
Make approval checks part of your trading routine
For repeated Base trades, check the allowance once before trading a token through a contract you trust. When the same approval logic applies to a base swap exchange, it can help you avoid an unnecessary transaction; one quick check can save a step without granting more access than you intend.