# ACH Processing Flow

## Steps in the ACH Processing Flow

1. **File Ingestion:** ACH files are received and validated.
2. **Effective Entry Date Validation:** Ensures the transaction date is valid.
3. **Settlement Date Calculation:** Determines when funds are settled.
4. **Same-Day ACH Handling:** Processes eligible same-day transactions.
5. **Batch Posting:** Posts transactions to the appropriate accounts.

## Sequence Diagram

```mermaid
sequenceDiagram
    participant Originator
    participant ODFI
    participant ACHNetwork
    participant RDFI
    participant CoreSystem

    Originator->>ODFI: Submit ACH File
    ODFI->>ACHNetwork: Transmit File
    ACHNetwork->>RDFI: Deliver File
    RDFI->>CoreSystem: Post Transactions
```

This diagram illustrates the flow of ACH transactions from the originator to the core system.