What the standards actually are
ERC-20 and TRC-20 are token standards, not coins. They describe how a token behaves on Ethereum and on Tron. USDT is issued on both, so the same dollar balance exists twice — once per network, each with its own address format and its own network fee.
How to choose
- Small, frequent payments → TRC-20. Confirmation takes seconds and the fee is a few cents, which matters when the invoice is $20.
- Large transfers, exchanges, DeFi → ERC-20. It is supported everywhere and audited by every tool, at a higher fee.
- Whatever your counterparty asked for. The invoice, exchange or wallet dictates the network. Matching it is not optional.
The mistake that costs money
Sending USDT to an address on the wrong network. An Ethereum address (0x…) and a Tron address (T…) look nothing alike, but wallets accept a pasted address without knowing where you meant to send it, and the funds land on a chain where nobody controls it. Recovery is rare and slow.
Two habits prevent almost every incident: copy the address and the network from the same invoice, and send a small test transfer the first time you pay a new counterparty.
What a checkout should do for you
A payment page should name the network next to the address, encode both in the QR code, and expire the invoice if the rate moves too far. If it auto-converts, the network fee is taken from the payment and the settlement figure you see is what reaches your balance.