Most of the rails in this course settle on a delay. ACH batches and settles hours later. Card networks authorize now and settle in a separate cycle. Fedwire settles in real time but only runs on a business calendar. Instant payments break that pattern in two ways at once: the money moves in seconds, and it moves at 2 a.m. on a Sunday. That combination, always-on plus immediately final, is the whole point, and it reshapes your funding, your fraud controls, and your exception handling.
There are two such rails in the US: the RTP network, run by The Clearing House and live since 2017, and the FedNow Service, run by the Federal Reserve and live since July 2023. They are operationally separate. A payment does not cross between them. If you want full reach, you connect to both.
What "instant" actually means here
Three properties travel together, and it helps to keep them distinct.
24/7/365. Both rails are open every hour of every day, including weekends and holidays. There is no cutoff window and no settlement day to wait for.
Real-time gross settlement. Each payment is settled individually and immediately, not netted into a batch. There is no deferred net position that unwinds at end of day.
Settlement in central bank money. The interbank leg settles on the books of a Federal Reserve Bank, not across a commercial correspondent's ledger. That is what makes the payment final rather than merely promised.
Put together: the receiver's funds are good funds the instant the payment posts, any day, any hour.
Credit-push only
Neither rail supports debit pull. You cannot reach into another institution's account and take funds. Every transaction is a credit push: the sending institution moves money out on the sender's instruction.
This is a deliberate design choice, not a missing feature. Debit pull is what makes ACH and card networks vulnerable to unauthorized origination and what creates the need for a returns-and-disputes apparatus. By allowing only pushes, the rails remove an entire fraud surface at the protocol level.
Both rails support a Request for Payment message, which lets a biller ask to be paid. But the RfP is just a message. It does not move money. The payer's institution still has to push a credit in response. The control stays with the sending side.
Instant finality, and what it costs you
Once an instant payment settles, it is irrevocable. There is no chargeback, no ACH return window, no clawback at the network level. The funds are gone and they are the receiver's.
That is excellent for the receiver and unforgiving for everyone responsible for stopping bad payments. With cards, the network gives you a dispute process after the fact. With instant payments, your only real control point is before the push leaves. If a customer is socially engineered into sending money to a fraudster, the money is final the moment it lands, and recovery depends entirely on the receiving institution's willingness and ability to cooperate.
Refunds, when legitimate, are handled as a fresh payment in the opposite direction or through a request-for-return message, not a reversal. A "refund" is a brand new credit push. There is no mechanism that reaches back and undoes the original.
Plan your fraud controls around the assumption that every approved payment is permanent at the instant it settles. The leverage is all pre-transaction: name verification, limits, velocity checks, and confirmation of payee.
A concrete example
A title company sends $400,000 to close a real estate purchase over RTP at 7 p.m. on a Friday. The credit lands in the seller's account within seconds and is final. The seller can wire it onward that evening.
Now run the same flow with a compromised email in the chain and a fraudulent account number. The $400,000 settles, finally, into the fraudster's account before anyone reviews anything. There is no Monday-morning return file to catch it. This is why high-value instant payments lean so heavily on payee confirmation and out-of-band verification. The rail gives you speed and certainty; it gives you no second look.
Funding models: the real operational difference
Both rails settle in central bank money, but they get there differently, and this is where RTP and FedNow genuinely diverge.
FedNow settles directly in each institution's own Federal Reserve master account (or a correspondent's master account if the institution settles through one). When a payment clears, the Fed debits the sender's master account and credits the receiver's, in real time. There is no separate pool to prefund. The institution manages liquidity in the account it already holds, and FedNow offers liquidity management transfers to move funds in and out around the clock.
RTP uses a single prefunded joint account at the Federal Reserve Bank of New York, jointly owned by participating institutions. Each participant maintains a position in that pool. When a payment clears, RTP decreases the sender's position and increases the receiver's, backed dollar-for-dollar by the prefunded balance. Participants top up the pool by sending funds over Fedwire during Fedwire hours, which means weekend and overnight funding has to be provisioned in advance. If your position runs low at 3 a.m. Sunday, you cannot replenish it until Fedwire reopens, so you size the prefunded balance to ride through the closed window.
The practical takeaway: FedNow ties liquidity to the master account you already run; RTP asks you to pre-stage liquidity in a shared pool and manage it against Fedwire's calendar.
Transaction limits
Limits have climbed as the rails take on higher-value use cases. The RTP network raised its per-payment limit to $10 million in early 2025. FedNow, which launched with much lower limits, raised its limit to $1 million in mid-2025 and then to $10 million in November 2025. Both numbers move over time and are set by the operators, so confirm the current figure before you build a product around a specific ceiling.
Takeaway
RTP and FedNow give you the same core promise, instant, irrevocable, around-the-clock settlement in central bank money, on a credit-push-only design. The engineering difference is funding: FedNow settles in your own Fed master account, RTP settles in a shared prefunded account you stage in advance against Fedwire hours. The operational difference is that finality moves all your risk to the moment before send. Build the controls there, because once the payment clears, there is nothing left to claw back.