What is same-day ACH?
Same-day ACH is a settlement option within the US ACH network that allows payments to be submitted and settled within the same banking day, rather than the standard one- to two-day cycle. It launched in September 2016 for credits, with debits added in 2017. The current per-payment limit is $1 million (USD), applying to both credits and debits.
In 2025, same-day ACH processed 1.4 billion payments valued at $3.9 trillion, representing year-over-year growth of 16.7% by volume and 21.4% by value. It is one of the fastest-growing segments of the ACH network and is increasingly used for payroll, B2B payments, and time-sensitive disbursements.
How does same-day ACH work?
Same-day ACH uses the same underlying ACH infrastructure as standard ACH, but payments are submitted into one of three dedicated intraday processing windows. Each window has an ODFI (Originating Depository Financial Institution) submission deadline and a corresponding settlement time.
The three windows, based on Eastern Time, are:
- Window 1: ODFI deadline 10:30 a.m. ET, settlement at 1 p.m. ET
- Window 2: ODFI deadline 2:45 p.m. ET, settlement at 5 p.m. ET
- Window 3: ODFI deadline 4:45 p.m. ET, settlement at 6 p.m. ET
The third window was added in March 2021 to extend same-day access later into the business day. All RDFIs are required to receive same-day ACH payments, which means an originator can reach every US bank and credit union account via same-day settlement, unlike some instant payment rails that require bilateral enrollment.
Most payment types are eligible, with one notable exclusion: international ACH transactions (IATs) cannot be submitted as same-day entries.
Same-day ACH vs. standard ACH: what's the difference?
Standard ACH settles on a next-day or two-day cycle depending on the entry type and submission timing. Same-day ACH compresses that window to within a few hours of submission. For fintechs and PSPs processing USD flows, the practical difference is the cut-off time risk: a payment missed for same-day processing falls back to next-day settlement.
The other meaningful difference is cost. Same-day ACH entries carry a per-transaction fee paid by the ODFI to the RDFI, set under the NACHA Operating Rules. Standard ACH entries do not carry this fee. Fintechs passing ACH costs through to end users need to account for this differential in their fee models.
What is the same-day ACH dollar limit?
The current per-payment limit for same-day ACH is $1 million, raised from $100,000 in March 2022. Entries submitted above the $1 million threshold in a same-day window are not rejected; they are automatically downgraded to next-day settlement by the ACH operator.
Nacha has proposed increasing the per-payment limit to $10 million, with a proposed effective date of March 19, 2027. The proposal is intended to align same-day ACH with RTP and FedNow, both of which raised their per-payment limits to $10 million in 2025. If adopted, it would make an estimated $7 to $8 trillion in additional ACH volume eligible for same-day settlement annually.
Why same-day ACH matters for fintechs
For fintechs building USD payment products, same-day ACH fills a gap between standard ACH and instant rails like RTP and FedNow. It reaches the full US banking system, unlike instant rails that depend on participating institution enrollment. Key operational considerations include:
- Payroll corrections: Missed or erroneous payroll runs can be remediated on the same day without issuing paper checks
- B2B settlement: Time-sensitive vendor payments and invoice settlements below the $1 million threshold can clear within hours
- Return speed: Same-day windows can also be used to transmit ACH return codes faster, reducing liquidity exposure for RDFIs and giving originators earlier notice of failed entries
- Cut-off management: Three daily windows give payment platforms more flexibility when handling late-submitted or corrected entries
For a broader view of how ACH fits alongside instant rails in USD infrastructure, see our guide to understanding ACH payments and our overview of electronic funds transfers.
