How to add the fiat last mile to a Fireblocks, Circle, or Paxos stack

To add the fiat last mile to a Fireblocks, Circle, or Paxos stack, connect the wallet that holds your stablecoins to BlindPay and let BlindPay pay local currency into the recipient's bank: Pix in Brazil, SPEI in Mexico, ACH Colombia, Transfers 3.0 in Argentina, ACH and RTP in the US, SEPA in Europe, Faster Payments in the UK, and SWIFT (POBO/COBO) everywhere else. There are two ways in: a quote and an approve signed from a Fireblocks vault, or a BlindPay offramp wallet that any custody account can send USDC or USDT to.

Custody platforms are built to hold and move tokens. Getting reais into a Brazilian bank account in seconds is a different job. This guide covers both paths, which one fits each custody setup, and the mistakes that cost a payout.

Key takeaways

• Fireblocks, Circle, and Paxos hold the stablecoins. BlindPay converts them and pays the bank on the local rail.
• From a Fireblocks vault, use the quote path: register the vault address, quote, approve, execute. The rate and fees are locked for 5 minutes.
• From Circle Mint or Paxos, use an offramp wallet: send USDC or USDT to its deposit address and BlindPay pays the linked bank account automatically.
• The keys never leave your custody platform. BlindPay executes only the amount you authorize.
• Track three IDs per payout: payout ID, on-chain hash, and rail reference, plus the UETR and MT103 on SWIFT.

What is the fiat last mile in a stablecoin stack?

The fiat last mile is the step where stablecoins become local currency in a recipient's bank account. Everything before it, minting, custody, moving tokens between chains, happens on-chain. The last mile happens on a bank rail, and each country has its own: Pix in Brazil, SPEI in Mexico, ACH in the US, SEPA in Europe.

Custody platforms point to partners for this step. The Fireblocks Network directory lists providers "offering local payment rails, blockchains, on/off-ramps, liquidity, FX, and remittance capabilities". Circle Payments Network routes payouts through global payout partners. A direct BlindPay integration puts that step in your own API calls: you pick the rail per country, see the quote, and get the rail reference back.

Which path fits your custody setup?

Most teams use both. The quote path covers one-off transfers where the customer needs a firm number on screen. The offramp wallet covers recurring flows, like a monthly settlement to the same supplier, where nobody needs to press a button.

How do you pay out from a Fireblocks vault?

The vault keeps its keys, and every signature comes from the Fireblocks API.

1. Create the customer and the bank account. Onboard the customer with KYC or KYB, then add the recipient's bank account with the fields its rail needs. See bank accounts.
2. Register the vault address. Fetch the challenge from BlindPay's sign-message endpoint, sign it from the vault as a typed message, and submit the signature. BlindPay recovers the address and stores it as a blockchain wallet.
3. Request a payout quote. The quote locks the rate and fees for 5 minutes and returns the approve payload: token contract, spender, and amount. See payout quotes.
4. Approve the token pull. Send the approve as a Fireblocks contract call from the vault account and wait for it to complete. Transaction Authorization Policy rules and cosigner approval add time here.
5. Execute before the quote expires. Call the EVM payout endpoint with the quote ID and the vault address. If approval ran past 5 minutes, request a new quote. If the allowance already on-chain covers the new amount, skip the second approve.
6. Track it to the bank. Payout webhooks report each status. Store the rail reference, and on SWIFT the UETR and MT103, against the ledger entry.

The Integrate Fireblocks with BlindPay prompt hands this whole flow to a coding agent, including the expiry race and test amounts for a development instance.

How do you pay out from Circle Mint or Paxos?

Use a BlindPay offramp wallet. It is a deposit address tied to one bank account: anything sent to it converts and pays out on its own.

1. Create the offramp wallet on the recipient's bank account and pick the network, for example Polygon for USDC or USDT, or Base for USDC. For SEPA and Faster Payments accounts, pick Ethereum, Polygon, Base, Arbitrum, or Solana.
2. Allowlist the deposit address at your custody platform. Circle Mint asks you to create a recipient address before it will transfer USDC on-chain, and Paxos uses saved withdrawal addresses.
3. Send USDC or USDT to that address. BlindPay creates the payout and pays the linked bank account over its rail.
4. Match the payout to the deposit by on-chain hash in your ledger.

Each network has its own additional fee, from 0 USDC on Polygon, Base, Arbitrum, Tempo, and Arc to 15 USDT on Tron, listed in the offramp wallets docs. Send amounts that clear every fee: a deposit smaller than the total fees stays at the deposit address instead of converting.

Which bank rails can the recipient get paid on?

BlindPay pays out over Pix, PIX Safe, and TED in Brazil, SPEI in Mexico, ACH Colombia, Transfers 3.0 in Argentina, ACH, RTP, and wire in the US, SEPA in Europe, Faster Payments in the UK, and SWIFT (POBO/COBO) globally, with UETR tracking and MT103 confirmations on SWIFT. The full table is in payment methods. For neobanks choosing which corridors to open first, which payout rails to launch first has a scoring method.

What mistakes break a last-mile payout?

• Letting the quote expire during approval. Fireblocks policy and cosigner steps can take longer than 5 minutes. Check the time left before you execute, and re-quote instead of retrying a stale quote.
• Pairing the wrong token and network. USDT payouts run on Ethereum, Polygon, Tron, Solana, and Tempo. On Base, Arbitrum, Arc, and Stellar, pay out in USDC. Check supported chains before you fund.
• Sending less than the fees to an offramp wallet. Small deposits stay at the address. Monitor for them.
• Skipping the development instance. Run the full flow with USDB on a testnet first. The test amounts $666.00 and $777.00 force a failed and a refunded payout, so your error handling gets exercised before real money moves.

Methodology and sources

BlindPay facts come from the EVM payout, blockchain wallets, payout quotes, offramp wallets, and supported chains docs. Custody-platform facts come from each provider's own pages, read on November 3, 2026: the Fireblocks Network directory, Circle Payments Network fiat payouts, Circle Mint on-chain transfers, and Paxos withdrawal addresses. For which provider fits each layer of a neobank, see the neobank stablecoin stack by layer.

What to do next

Pick the path that matches where your stablecoins sit. On Fireblocks, open a BlindPay development instance and run the Integrate Fireblocks with BlindPay prompt end to end. On Circle Mint or Paxos, create one offramp wallet on a test bank account and send a small USDB deposit to it.