## TL;DR

When NetSuite marks a custom segment as mandatory, every vendor bill (and often every line) must carry a value for it or the transaction fails validation. Find which segment is required and at what level (header, line, or both) in the segment definition, then supply valid values from the segment's list on every bill you import. The common failure is a new mandatory segment added by an admin that the integration does not know about. Keep a segment manifest in your integration config and validate bills against it before posting.

## The query

```text
NetSuite custom segment required on vendor bills: how to satisfy it
```

## Use this when

- Vendor bill imports failing on a required custom segment
- New mandatory segment breaking the AP integration
- Finding which segment level requires a value

## Not for

- Standard classification errors (department, class, location)
- Custom field (not segment) requirements

## Steps

1. Identify the required segment and whether it applies at header, line, or both.
   Expected output: You know exactly what must be populated.
2. Get the valid value list for the segment.
   Expected output: You are choosing from real values, not guessing.
3. Map your source data to segment values (cost center mapping, project codes).
   Expected output: Every bill has a deterministic value.
4. Populate the segment on the bill header and lines as required.
   Expected output: Validation passes.
5. Store the segment manifest in your integration config and alert when definitions change.
   Expected output: The next new mandatory segment does not blindside you.

## Variant phrasings

### NetSuite custom segment required vendor bill

### mandatory custom segment transaction NetSuite

### custom segment validation failed bill import

## Root cause

Custom segments are NetSuite's dimensional accounting: making one mandatory means finance requires that dimension on every transaction for reporting. The integration breaks because it was built against yesterday's dimension list, so the fix is keeping a manifest, not hardcoding values.

## Edge cases

- Segments can be required conditionally by subsidiary; check the subsidiary context
- Scripted defaults can fill segments, but explicit values audit better

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_3UI2H_OWPl9ejNzA_y9vxA