Stablecoin settlement

Stablecoin settlement is completing a payment by transferring a token that is pegged to a fiat currency, such as a US dollar stablecoin, from the payer’s blockchain address to the payee’s.

What a stablecoin is. In the United States, the GENIUS Act (Public Law 119-27, signed 18 July 2025) sets up a regulatory framework for payment stablecoins: digital assets that the issuer must redeem for a fixed value. Only permitted issuers may issue them for use by US persons, subject to exceptions, and issuers must hold one-to-one reserves in US currency or similarly liquid assets.

How it works in x402. x402 is one protocol that settles agent payments this way. In its exact scheme on EVM chains, the preferred method is ERC-3009’s transferWithAuthorization, which tokens such as USDC implement:

1. The client signs an authorization naming the sender, recipient, amount, a validity window and a random 32-byte nonce.
2. A facilitator verifies the signature, the payer’s balance, and that the amount, window, token and network match the server’s requirements.
3. The facilitator submits the transfer on chain and pays the gas. It cannot change the amount or the destination, because the client’s signature covers them.

For tokens without ERC-3009, the scheme falls back to Permit2 through a proxy contract that only pays the address the client signed for. The settlement result names the transaction hash and the network:

{
  "success": true,
  "transaction": "0x1234567890abcdef1234567890abcdef1234567890abcdef1234567890abcdef",
  "network": "eip155:84532",
  "payer": "0x857b06519E91e3A54538791bDbb0E22373e36b66"
}

Finality and follow-up. Settlement is done when the chain confirms the transfer. If a facilitator broadcasts the transaction but cannot confirm it, x402 lets it report settlement_pending with the transaction hash, so the caller can check the chain before retrying and avoid paying twice. Neither ERC-3009 nor the x402 core specification defines a reversal, so a refund is a separate transfer back to the payer. Card payments differ here: the card networks run a chargeback process after settlement.

Neighbouring terms. Settlement in general covers card and bank rails too. Reconciliation matches on-chain records against orders and books.