Same-Day ACH is an expedited variant of the US ACH network that clears and settles credit and debit transfers within the same business day across three Nacha-mandated settlement windows, with a per-transaction limit of approximately 920,000 euros (USD 1M).
Same-Day ACH is the expedited tier of the US Automated Clearing House network, governed by Nacha (the National Automated Clearing House Association). Unlike traditional ACH, which settles one to two business days after origination, Same-Day ACH clears and settles within the same business day, provided the originating bank submits the file before one of the three daily cutoffs.
Since the March 2022 expansion, there are three settlement windows each business day. The first window cuts off at 10:30 AM ET and settles at 1:00 PM ET. The second window cuts off at 2:45 PM ET and settles at 5:00 PM ET. The third and most popular window cuts off at 4:45 PM ET and settles by 6:00 PM ET. AR teams that originate debit pulls in the final window can collect customer funds before the close of the same business day, materially compressing days sales outstanding.
Same-Day ACH retains the batch architecture of legacy ACH. Files contain multiple credit or debit entries, and settlement happens in bulk through the Federal Reserve. It is not a real-time payment rail, but it is dramatically faster than the one-to-two-day standard cycle and far cheaper than wire transfer.
The per-transaction limit for Same-Day ACH is USD 1,000,000, or roughly 920,000 euros, raised from USD 100,000 in March 2022. The limit applies per entry, so larger settlements can be split across multiple entries within the same file or across windows.
Nacha governs the operating rules, including return-code definitions, file formats (NACHA-formatted flat files using the standard entry class codes such as CCD for corporate-to-corporate and PPD for consumer payments), and mandatory participation. Every US receiving depository financial institution must accept Same-Day ACH entries. Origination, by contrast, is optional, so AR teams should confirm their bank supports Same-Day origination and which windows are exposed through their cash management portal or API.
The most common B2B AR use case is collecting customer payments on the invoice due date via ACH debit, with prior authorization, so funds land the same day rather than two days later. This is particularly valuable for high-value invoices where one or two days of float on a seven-figure balance represents meaningful interest.
Other use cases include same-day payroll runs that previously required wire transfer, last-minute supplier payments timed to capture early-payment discounts (typical terms such as 2/10 net 30 are worth roughly 36 percent annualised), insurance claim payouts where settlement speed affects customer satisfaction, and same-day tax payments to meet filing deadlines without wire fees.
Wire transfer is real-time and settles individually rather than in batches, with no daily cap, but typically costs 25 to 50 euros or more per transaction and requires manual initiation for each payment. Wire is the right choice when speed within a window is more important than cost, or when the value exceeds Same-Day ACH limits.
FedNow, launched in July 2023 by the Federal Reserve, offers real-time settlement 24/7/365 with a default cap of USD 500,000 (raised in 2024). RTP, operated by The Clearing House since 2017, also runs 24/7/365 with a cap raised to USD 10,000,000 in 2025. Both are instant rails: funds move and finalise within seconds, with no batching and no settlement windows.
Same-Day ACH sits between traditional ACH and the instant rails. It is the right choice when same-day is sufficient and the volume justifies batch efficiency. For B2B AR runs processing hundreds or thousands of entries, the cost difference between Same-Day ACH at sub-euro pricing and instant rails at 0.25 to 1 euro per transaction adds up quickly. For weekend or after-hours collections, only FedNow and RTP work, since Same-Day ACH does not run on weekends or federal holidays.
The most frequent operational mistake is missing the 4:45 PM ET cutoff. Files submitted at 4:46 PM ET settle the next business day, defeating the purpose of the upgrade. AR teams should automate file submission well before the cutoff and build buffer time for bank processing.
The second mistake is treating Same-Day ACH as a wire substitute and forgetting that it remains a batch rail. Reconciliation files still arrive in NACHA format and must be parsed, not read as individual confirmations.
The third mistake is mishandling return codes. Nacha return codes range from R01 (insufficient funds) and R02 (account closed) through R85 (incorrectly coded outbound international payment). R01, R02, R03 (no account), and R09 (uncollected funds) account for the bulk of B2B returns. Teams must code returns properly in their AR system, decide whether to retry (Nacha permits up to two retries for R01 and R09 within 180 days), and update the customer master with verified bank details when R02 or R03 fires. Returns typically arrive one to two business days after origination, which means AR cash forecasts should not assume Same-Day ACH funds are final until the return window has closed.
Agentic AR platforms apply machine reasoning to three Same-Day ACH workflows. First, they recommend optimal payment timing: when a supplier offers an early-payment discount expiring today, the platform automatically routes the disbursement to the 4:45 PM ET window so AP can capture the discount without burning float. Second, they automate return-code handling: when an R01 hits, the agent checks the customer's payment history, decides whether to retry in the next window, and notifies the collector if a manual call is warranted. Third, they apply credits to invoices in real time by polling bank files at each settlement window, matching incoming Same-Day ACH credits against open AR using remittance data, and clearing invoices the same day. Combined, these workflows can compress DSO by one to two days on the Same-Day-enabled portion of receivables and reduce return-handling labour by up to 70 percent.
Same-Day ACH is the expedited tier of the US ACH network. It clears and settles within the same business day across three Nacha-mandated windows, whereas traditional ACH takes one to two business days. The format, file structure, and return-code logic are otherwise identical.
There are three windows each business day. Window one cuts off at 10:30 AM ET and settles at 1:00 PM ET. Window two cuts off at 2:45 PM ET and settles at 5:00 PM ET. Window three cuts off at 4:45 PM ET and settles by 6:00 PM ET. Same-Day ACH does not run on weekends or federal holidays.
The per-transaction limit is USD 1,000,000, equivalent to roughly 920,000 euros. Nacha raised the limit from USD 100,000 in March 2022. Larger amounts can be split across multiple entries or sent via wire, FedNow, or RTP.
Yes. Same-Day ACH typically costs 0.50 to 5 euros per transaction, while wires usually cost 25 to 50 euros or more. For high-volume B2B AR runs, Same-Day ACH delivers same-day funds at a fraction of the wire cost, with the trade-off that it is batch-based rather than real-time.
FedNow and RTP are instant rails that settle 24/7/365 in seconds, with caps of USD 500,000 and USD 10,000,000 respectively. Same-Day ACH is a batch rail with three daily windows and a USD 1,000,000 cap, available only on business days. It is the right choice when same-day timing is enough and batch economics matter.
The highest-frequency B2B return codes are R01 (insufficient funds), R02 (account closed), R03 (no account or unable to locate), and R09 (uncollected funds). Nacha permits up to two retries for R01 and R09 within 180 days. R02 and R03 require updating the customer master with verified bank details before resubmission.
