Tax workpaper redaction is the removal of taxpayer data from a preparation file whose confidentiality reflects CRCA 2005 s.18. That section binds HMRC officers not to disclose a client's identity or figures. anonym.plus marks each identifier on your device, so the computation trail stays while protected data goes.
When this applies
A prep workpaper carries the client's NI number, prior-year figures, and source documents. You strip that protected information before a reviewer opens it.
How anonym.plus handles it
- Open the prep file in anonym.plus on your device.
- Built-in OCR reads scanned source documents.
- The app marks the NI number, UTR, name, and address.
- Keep the computation steps and reconciling notes.
- Mask the NI number or swap it for a label.
- Save the clean file locally.
What you need to provide
- The prep file (PDF, XLSX, DOCX, scan).
- An operator: Mask keeps only the suffix of an NI number.
- Optional batch for a folder of source documents.
PII & financial identifiers detected
| Category | anonym.plus entity type | Example |
|---|---|---|
| Identifiers | UK_NINO | QQ 45 21 77 D → QQ XX XX XX D |
| Tax reference | NATIONAL_ID | client UTR → [UTR] |
| Names | PERSON | client Maeve Orr → [TAXPAYER] |
| Location | LOCATION | client address → [ADDRESS] |
| Money | MONEY | total income £112,400 → [AMOUNT] |
| Dates | DATE_TIME | prior yr 2025 → [YEAR] |
Compliance achieved
- Reflects the confidentiality duty in CRCA 2005 s.18.
- Masks the NI number and UTR that anchor a client's identity.
- Offline work keeps protected data off any server.
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Limitations & cautions
Section 18 binds officials, yet a shared prep file still carries identity and figures. A unique prior-year amount can hint at a client. The app marks named items; scan the computation notes before you share.
Frequently asked questions
What counts as protected data in a prep file?
The client's identity, the figures, and HMRC-sourced data. anonym.plus marks those identifiers so a shared copy keeps the same confidentiality.
Can I keep the computation steps?
Yes. Allow-list the computation columns. Only personal identifiers, not the logic, are marked.
Is the prep file uploaded?
No. The app is fully offline, so the client's data stays on your device.