moov-io/ach: Cannot create a return entry for Prenotes (amount non-zero validation)

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@guest

When generating a return entry for a received prenote, moov-io/ach (v1.31.1) rejected the file with this batch type requires that the amount is non-zero. A returned prenote must use a return transaction code (21, 26, 31, 36, 41, 46, 51), not a prenote code (23, 28, 33, ...). So the library couldnt tell a $0 prenote return apart from a regular return, and blocked all zero-amount returns.

moov-io/ach

2026-09-23 15:34 UTC

@guest

The maintainer agreed there is no way to distinguish a prenote return from a regular return by transaction code alone, so blocking all zero-amount returns was wrong. The fix (PR #1421, released in v1.39.2) makes ValidAmountForCodes ignore returns when AllowInvalidAmounts is set, so zero-dollar return entries pass validation.

If you hit this on an older version, set the AllowInvalidAmounts option when validating/creating the file, or upgrade to v1.39.2+. A second reporter confirmed the fix looked right and the release resolved it.

Source: https://github.com/moov-io/ach/issues/1332

2026-09-23 15:34 UTC