ACH File Converter

ACH File Validator

Check structure, routing numbers, hashes, totals, trace numbers and control records.

1

Source ACH/NACHA file

Resolve the validation result

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Checks applied to each record and batch

Physical records

The validator checks 94-character record length, recognized record types, line structure, ordering, and the relationship between headers, entries, addenda, and controls.

Payment fields

Routing-number checksums, transaction codes, amounts, SEC-code context, effective dates, addenda indicators, and trace-number structure are reviewed where the parsed data supports the check.

Control reconciliation

Stored counts, entry hashes, debit totals, credit totals, batch numbers, block count, and type 9 padding are compared with values calculated from the records.

What errors, warnings, and review items mean

An error identifies a structural or arithmetic inconsistency that should be corrected before transmission. A repairable finding is a deterministic issue, such as controls or padding, that can be rebuilt without changing payment instructions. A review item highlights unusual or bank-dependent data that requires human judgment.

Repeated symptoms should be read as one root-cause chain. For example, a truncated line can make later fields appear invalid; correcting the record boundary may resolve several downstream messages.

What a clean result does not prove

  • The receiver authorized the entry.
  • The routing and account combination is active or owned by the receiver.
  • The company is enrolled for the chosen SEC code.
  • The effective date meets the bank cutoff and processing window.
  • The ODFI will accept every identifier or balancing convention.

Next steps after a failed check

Use the repair tool for deterministic controls, line endings, and padding. Use the editor when an authorized person must correct a supported payment field. Preserve the original, validate the revised copy, and reconcile entry counts and totals before transmission.

Questions about ACH validation results

Can a partially invalid file still be inspected?

Often, yes. Parseable records can produce useful diagnostics, but severely truncated, binary, encrypted, or incorrectly encoded input may need to be exported again.

Why does one bad line create several findings?

Fixed-width fields depend on record boundaries. One missing or extra character can shift multiple fields and produce routing, amount, trace, and control symptoms.

Does the validator change the uploaded file?

No. Validation reads the source in browser memory. Any repair or edit creates a separate output so the original can remain the audit baseline.

Why can a valid file still be rejected?

A bank can enforce originator enrollment, identifiers, SEC-code permissions, effective dates, balancing, risk controls, and transmission rules beyond file structure.

Which authoritative sources support this page?

Technical explanations are checked against these primary sources. Bank-specific requirements can be narrower than general format guidance.

  1. Nacha ACH File Details — Official record-field guidance, including Batch Header SEC codes and addenda capabilities.
  2. Nacha ACH File Overview — Official explanation of files, batches, entries, controls, and batch grouping.
  3. Nacha: How ACH Works — Official overview of ACH participants, consumer and corporate payments, and authorization responsibilities.
  4. Nacha Operating Rules Topics — Current rule changes and implementation topics published by Nacha.

Sources reviewed August 20, 2026. Nacha owns and maintains the linked materials.