Nagaris scans every workpaper for tax file numbers (TFNs) before it writes the final workbook. This article covers what trips the scan, what a hit looks like, and the two cases that still stop a workbook outright.
The scan only trips on a digit run that passes the ATO checksum for a TFN, inside a TFN-shaped pattern: spaced, hyphenated, or plain, including runs that sit next to a date or an amount.
A digit run that looks TFN-shaped but fails the checksum is not a TFN. It composes into the workbook untouched, as raw text.
Finding a valid TFN no longer stops the whole workpaper. Instead, for each cell that contains one:
The cell composes masked, not raw. A 9-digit TFN shows as XXX XXX 123 (the last three digits stay visible); an 8-digit TFN shows as XX XXX 123.
Nagaris raises one numbered query per distinct TFN value. The query's ID is keyed on the masked form, so it stays the same across re-runs of the same workpaper.
That query sits in the to clear lane, alongside the workpaper's other exceptions.
The workbook still writes. A TFN hit no longer halts composition.
After masking, Nagaris re-scans the composed output. If anything still matches a TFN pattern, the run halts. This catches a mask that leaks digits, or any value the first pass missed.
Every export surface carries the masked form only, never the original digits:
Surface | Field |
|---|---|
Workbook |
|
Sidecar file |
|
Summary |
|
Two situations stop composition outright and can't be overridden:
The organisation's own TaxNumber appears in a cell. This isn't a pattern guess, it's a known value, so a match means a real leak. Composition halts.
The post-mask convergence scan still finds a match. If a masked cell still matches a TFN pattern, something leaked, and the run halts rather than writing a workbook that isn't actually masked.
A reviewer can release a specific masked value so it composes unmasked instead of staying flagged. Nagaris records this as a reviewed exception, stamped per cell with:
The value
The reviewer's reason
Who released it (released_by)
The date of the run
This is the only way a TFN composes unmasked. Everything else that trips the checksum stays masked in the workbook.
