[Glossary](https://blnkfinance.com/glossary) Nacha file # What is a Nacha file? Nacha file A Nacha file is the fixed-width batch file banks exchange to originate ACH. It lists credits, debits, prenotes, returns, and NOCs. Your processor may hide the file behind an API. The settlement and the returns still arrive as that format, or as a report derived from it. Reconciliation reads those lines. ## How does a Nacha file work? Entries are grouped into batches with a company name, an SEC code, and an effective date. The file has a hash total so the operator can reject a truncated upload. Returns and NOCs come back in later files. You match them to the originals by trace number. ## Nacha file vs the API An ACH API writes the file for you. You still need the report. If you only store the API response, you will miss returns that arrive two days later in a file you never downloaded. ## What do you match? Amount, trace, direction, and your reference if you put it in the addenda. Weak matches on amount and date will pair the wrong two rows. ## How it works with Blnk Upload the Nacha or the processor’s ACH report in [reconciliation](https://docs.blnkfinance.com/reconciliations/overview). Match each line to the committed or voided transaction. Keep the trace number in metadata when you originate. Related terms - [ACH](https://blnkfinance.com/glossary/ach) - [Reconciliation](https://blnkfinance.com/glossary/reconciliation) - [SEC code](https://blnkfinance.com/glossary/sec-code) - [Batch processing](https://blnkfinance.com/glossary/batch-processing) - [Notification of Change](https://blnkfinance.com/glossary/notification-of-change)