01What exactly does CF-15 check? What if my export doesn't have separate numerator and denominator columns?
CF-15 requires that the export contains the apportionment factor, the numerator, and the denominator as separately exported columns. For multi-state apportionment exports that include entity-level detail — including certain CCH Axcess, GoSystem RS, and ONESOURCE export formats — these columns are present. For exports that don't include separate numerator and denominator columns, CF-15 is skipped and the diagnostic runs CF-01 through CF-14 only. The diagnostic tells you which checks fired on your specific file. No claims are made about files where the required columns aren't present.
02How do you determine the cause code — OVERRIDE_SUSPECTED vs. ROUNDING vs. EXPORT_DELTA?
Cause codes are diagnostic classifications based on variance magnitude and pattern — not definitive determinations. ROUNDING: variance under 5 bps with no sign change, consistent across multiple rows — consistent with rounding accumulation across a rollup. EXPORT_DELTA: variance pattern differs between states for the same entity — consistent with transformation between source system and export format. OVERRIDE_SUSPECTED: variance over 5 bps with no structural explanation found in the export columns — the most likely cause is a manual entry at the factor level not reflected in the exported numerator/denominator. All cause codes require human verification at the source system before action. The Export Exception Summary states this explicitly on every output.
03If the factor is mathematically correct, why does this matter?
Because "correct" and "documentable" are different standards. A factor is correct if it produces the right result on the return. A factor is documentable if the path from source data to that result can be independently verified. Standard review confirms the first. CF-15 checks the second. The gap matters in three specific situations: state exam — an examiner asking for a source-to-return walkthrough will find the gap if it exists; prior-year re-derivation — a restatement or amended return requires re-deriving the factor from source, which fails if the factor can't be re-derived from the export; client inquiry — a CFO or controller asking to reconcile the payroll factor against internal records will surface the variance. None of these situations are common. All of them are expensive when they occur.
04Does this integrate with CCH Axcess, GoSystem, or ONESOURCE directly?
No — and that's intentional. The diagnostic runs on exported files, not live connections to your tax software. This means no API keys, no IT coordination, no firewall exceptions, and no vendor integration process. More importantly, running the check inside the same software that produced the export would use the same transformation logic — which is exactly what CF-15 checks against. The value of running this check independently of the source software is that it's independent. Your team exports as they already do for review, runs the diagnostic in-browser in 90 seconds, and generates the workpaper artifact before sign-off.
05What happens to the file?
Nothing is uploaded. The diagnostic runs entirely in your browser via WebAssembly — the file is processed in-memory and never transmitted to our servers. This is a technical architecture fact, not a policy statement. Your firm's IT team can verify zero outbound data transmission in under 60 seconds by opening the browser Network tab during a diagnostic run. A SHA-256 hash of the file is computed locally for workpaper provenance. No file content leaves your machine.
06What if we find the condition in a return we already filed?
The diagnostic is a pre-sign-off tool. Its purpose is to identify structural conditions before the partner signs. For returns already filed, the professional judgment about whether a finding requires amendment, disclosure, or documentation is entirely the firm's call — the diagnostic does not make filing recommendations and does not provide tax advice. What the Export Exception Summary provides is documentation that a structural review was performed and what it found. That documentation has value regardless of when it's created.
