## TL;DR

Split expenses must allocate 100 percent of the amount across lines, each with a valid cost center, and the validation fails when the lines do not add up or a line lacks a cost center. Open the split, check the allocation math, fix the percentages or amounts so they total exactly, ensure both lines carry cost centers, and resubmit.

## Error

```text
expense split across two cost centers failed validation
```

## Steps

1. Open the split expense and review each split line's amount and cost center. Expected: you see the allocation per line.
2. Add the split amounts and compare to the original expense total. Expected: the gap (over or under) is visible, often a rounding cent.
3. Adjust the lines so they sum exactly to the original total. Expected: the amounts add up to the penny.
4. Confirm each line has a valid, active cost center selected. Expected: no line shows an empty or invalid cost center.
5. Resubmit. Expected: the split validation passes and the expense routes for approval.

## When to use

- A split expense fails validation across two cost centers.
- Percentage splits leave a rounding remainder.
- One split line was left without a cost center.

## When not to use

- The user lacks access to one of the cost centers (an access problem).
- A cost center is deactivated (a master-data problem).
- The expense should not have been split at all.

## Tool compatibility

Applies across expense tools supporting split allocation (Expensify, Concur, Float, and others; current 2026 releases).

### Variant phrasings

### "split amounts don't total" validation error

The allocation math is off, usually by rounding. Fix the penny.

### split expense missing cost center on one line

Each line needs its own cost center. Fill the empty one.

### percentage split rejected in the expense tool

Percentages that do not sum to 100 fail. Adjust to total exactly.

## Why it happens

Split allocation is a small accounting equation: the parts must equal the whole, and every part needs a booking target. Rounding on percentage splits (33.33 plus 33.33 plus 33.33) and forgotten cost-center selections on added lines are the two classic failures. Validation runs at submit time because the tool cannot post an unbalanced split to the ledger.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_th4ko_PY6ev3lHkDPaNapw