ACH is a batch rail that settles in hours to days at very low cost and supports both debits and credits. RTP is a real-time credit-push rail that settles in seconds, is irrevocable, and costs more per transaction. ACH still moves far more dollars; RTP wins for time-critical payments.
ACH is the workhorse of US bank-to-bank payments - payroll, vendor payments, bill pay, B2B invoicing - moving over $80 trillion per year on a batch architecture that has existed since the 1970s. RTP, launched 2017, is the modern instant alternative for use cases where speed and finality matter more than cost.
The right choice depends on the use case: ACH for predictable, low-cost, high-volume; RTP (or FedNow) for time-sensitive or trust-sensitive payments where finality is valuable.
Side-by-side comparison
| Attribute | ACH | RTP |
|---|---|---|
| Operator | Nacha (rules), Fed & TCH (operators) | The Clearing House |
| Settlement speed | Same-day to 2 business days | Seconds |
| Operating hours | Business hours, business days | 24/7/365 |
| Direction | Debits and credits | Credits only (push) |
| Reversible? | Yes (returns, disputes) | No - irrevocable once settled |
| Per-transaction cost | Pennies | $0.045 (TCH-published) |
| Transaction limit | $1M for Same Day ACH | $1M |
| Typical use cases | Payroll, B2B, bill pay, account funding | Real-time payouts, insurance claims, instant disbursements |
High-volume, predictable, cost-sensitive payments where same-day or next-day settlement is acceptable.
Time-critical payouts, gig economy disbursements, insurance claims, and any use case where instant finality is the product.
Use ACH as the default for routine payments; reach for RTP (or FedNow) when speed, 24/7 availability, or finality materially improves the customer experience.
Frequently asked
Is Same-Day ACH the same as RTP?+
No. Same-Day ACH settles in three windows per business day, not in real time, and is still reversible. RTP settles in seconds, 24/7, and is irrevocable.
Can I pull funds via RTP?+
Not directly - RTP is credit-push only. To pull funds, use ACH debit or the RTP Request for Payment overlay (which prompts the payer to push).
Sources & References
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