4.5 Same Day ACH: Windows, Limits ($1,000,000) & Eligibility Rules

4.5 Same Day ACH: Windows, Limits ($1,000,000) & Eligibility Rules

Core Principle: Same Day ACH is a foundational network modernization capability that enables participating financial institutions to originate, clear, and settle ACH credit and debit transactions on the same calendar banking day. Governed by Article Two and Article Three of the Nacha Operating Rules, Same Day ACH provides rapid liquidity for payroll disbursements, emergency bill pay, person-to-person (P2P) transfers, account-to-account (A2A) rebalancing, and same-day exception processing.

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1. Evolution and Architectural Milestones

Same Day ACH was introduced through a phased national rollout to allow financial institutions and core software providers to adapt operational workflows:

                               Same Day ACH Evolution Timeline
  ┌──────────────┐    ┌──────────────┐    ┌──────────────┐    ┌──────────────┐    ┌──────────────┐
  │  Sept 2016   │    │  Sept 2017   │    │  March 2018  │    │  March 2020  │    │  March 2021  │    ┌──────────────┐
  │   Phase 1    │───►│   Phase 2    │───►│   Phase 3    │───►│ Dollar Limit │───►│ Third Window │───►│  March 2022  │
  │ Credits Only │    │ Debits Added │    │ 5:00 PM Local│    │ Raised to    │    │ (Late Window)│    │ $1,000,000   │
  │  $25K Limit  │    │  $25K Limit  │    │ Availability │    │   $100,000   │    │ Added        │    │ Limit Enacted│
  └──────────────┘    └──────────────┘    └──────────────┘    └──────────────┘    └──────────────┘    └──────────────┘

• March 2021 (Third Window Expansion): Nacha and the Federal Reserve introduced a late afternoon processing window extending submission deadlines by two hours, greatly benefiting West Coast institutions.
• March 2022 ($1,000,000 Limit): Nacha increased the per-transaction limit tenfold from $100,000 to $1,000,000, dramatically expanding corporate B2B and payroll utility.

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2. The Three Daily Processing and Settlement Windows

Same Day ACH operates across three discrete daily transmission windows. The table below details the submission deadlines, ACH Operator distribution targets, Federal Reserve net settlement times, and mandatory RDFI funds availability deadlines:

                         Daily Same Day ACH Windows Sequence (Eastern Time)

  10:30 AM         01:00 PM     02:45 PM         05:00 PM     04:45 PM         06:00 PM
  ODFI Window 1    Settlement   ODFI Window 2    Settlement   ODFI Window 3    Settlement
  Cutoff           Window 1     Cutoff           Window 2     Cutoff           Window 3
  ─────┬───────────────┬────────────┬───────────────┬─────────────┬───────────────┬──────►
       │ (Settle)      │            │ (Settle)      │             │ (Settle)      │
       ▼               ▼            ▼               ▼             ▼               ▼
   Avail: 1:30 PM Local         Avail: 5:00 PM Local          Avail: End of Day

Local Time Rule for Funds Availability (Article 3.3.1.2)

• Window 1 Credits: Funds must be available for withdrawal or cash disbursement to the consumer no later than 1:30 PM (RDFI local time).
• Window 2 Credits: Funds must be available no later than 5:00 PM (RDFI local time).
• Window 3 Credits: Funds must be available no later than the end of the RDFI's banking processing day (in time for overnight batch posting).

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3. The $1,000,000 Per-Transaction Limit & Anti-Structuring Rule

Effective March 18, 2022, the maximum dollar limit for any individual Same Day ACH entry is $1,000,000.00.

Application of the Limit

• Per-Entry Basis: The $1,000,000 cap applies to each individual Entry Detail Record (Type 6). A single batch can contain multiple $1,000,000 entries totaling tens of millions of dollars.
• Reversals and Returns Exempt: Standard return entries (R-codes) and automated reversals are exempt from the $1,000,000 dollar limit and can be processed via Same Day ACH regardless of amount.

Anti-Structuring Mandate

$\text{Prohibited Structuring:} \quad \text{Splitting a } \$2,500,000 \text{ payment into three Same Day entries } (\$900\text{k} + \$900\text{k} + \$700\text{k})$

• The Rule: Originators and ODFIs are strictly prohibited from breaking down, splitting, or structuring transactions exceeding $1,000,000 into multiple smaller Same Day entries to evade the dollar threshold.
• Operator Handling of Over-Limit Entries: If an ACH Operator receives an entry exceeding $1,000,000 with a current-day Effective Entry Date, the operator does not reject the file; instead, it automatically modifies the settlement date to next banking day standard settlement.

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4. Eligible vs. Ineligible SEC Codes

Virtually all domestic ACH Standard Entry Class codes are eligible for Same Day ACH processing, spanning consumer, commercial, and check conversion applications:

                                  Same Day SEC Code Eligibility
         ┌──────────────────────────────────────┴──────────────────────────────────────┐
         ▼                                                                             ▼
    ELIGIBLE SEC CODES (Credits & Debits)                                         INELIGIBLE SEC CODES (Strictly Excluded)
  • Consumer: PPD, WEB, TEL, CIE, POS, MTE, SHR                                 • IAT (International ACH Transactions)
  • Commercial: CCD, CTX                                                          (Cross-border OFAC & FX complexity)
  • Check Conversion: ARC, BOC, POP, RCK, XCK                                   • ENR (Automated Enrollment Entries)
  • Specialty/Non-Monetary: DNE, Prenotes, Returns

The Two Ineligible SEC Codes

1. IAT (International ACH Transactions): The Rules in force during the October 2026 exam window make IAT entries ineligible for Same Day ACH.
2. ENR (Automated Enrollment Entries): These non-dollar federal enrollment entries are also ineligible for Same Day ACH. XCK entries are not categorically excluded, although their separate application and dollar restrictions continue to apply.

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5. Participation Mandates & The Interbank Fee Structure

Universal RDFI Receipt Mandate vs. Optional ODFI Origination

• RDFI Mandatory Receipt: Every Receiving Depository Financial Institution (RDFI) in the United States is mandated to receive, process, and provide timely funds availability for incoming Same Day ACH entries. An RDFI cannot opt out.
• ODFI Optional Origination: Originating Same Day ACH entries is optional for ODFIs and their Originators.

Interbank Per-Entry Fee (5.2 Cents)

To compensate RDFIs for the technology upgrades, operational staffing, and liquidity demands required to support rapid intraday settlement, Nacha established a mandatory interbank fee:

• Amount: Fixed at 5.2 cents ($0.052) per Same Day entry.
• Flow: The ACH Operator automatically assesses the fee against the sending ODFI and credits the fee directly to the receiving RDFI during settlement.
• Returns Exempt: Same Day return entries are exempt from the interbank fee.