Fake P45 Detection — Catch Edited Leaver PDFs
A P45 sets the new starter’s tax code and pay-to-date — and an edited one cascades into payroll. New-employer HR teams trust the P45 the starter brings. Payroll uses it to set the tax code and the pay-and-tax-to-date for the year. When that P45 is fabricated or tampered, the error compounds across every payslip until HMRC eventually corrects it — and the discrepancy lands on someone’s desk.
HTPBE? analyzes the structural layer of the PDF file — the layer that records every edit, even invisible ones. We don’t inspect holograms, phone photos, or ID biometrics. If your fraud problem is a digitally altered or fabricated P45, we’re the most specific tool for it.
When HTPBE? returns INCONCLUSIVE on a P45, that’s itself a fraud signal in this context — real P45 exports always come from a UK payroll engine, never from a desktop tool.
The problem
Modern document fraud is invisible to visual review
A growing class of document fraud opens a genuine PDF, edits a balance, a date, or a beneficiary, and re-saves it. Visually nothing changes — the document passes pixel-level review, layout review, and KYC.
Structural PDF analysis reads the layers rendering engines never expose: revision history, object structure, signature coverage maps. That is where edits leave fingerprints they cannot wipe.
Common tampering patterns
- Modified balances or totals after export
- Swapped IBAN or beneficiary on invoices
- Post-signature edits on contracts
- Backdated issue and modification dates
- Fabricated documents from consumer PDF tools
What this looks like
How fake and tampered P45 PDFs actually look
Three real fraud mechanics we catch at the structural PDF layer.
Pay and tax to date edited up
Authentic P45 comes from the leaver’s previous employer payroll system. The new starter opens it in any PDF editor or spreadsheet, edits the Total pay to date or Total tax to date, exports as PDF. Producer field changes from the payroll engine to whichever editor was used. Visual layout preserved; file fingerprint flipped.
P45 fabricated to skip a gap of unemployment
There is a six-month gap between the real last working day and the new start date — the candidate was either out of work or working under the table. They build a P45 in Word using a template, type in plausible figures, export to PDF. Producer field shows Microsoft Word; structured payroll metadata is missing.
Tax code rewritten to favour the starter
A BR or D0 emergency code on the original P45 means more tax. The starter edits the code to their preferred letter (1257L, etc.) before submitting. Even when the visual layout is clean, incremental update markers in the xref chain expose the post-issuance edit.
The scale
Why your existing checks miss this
Payroll trusts the P45 figures. Trust them too readily and the error cascades.
HMRC eventually flags the discrepancy. By then payroll has been paying the wrong figures for months.
New-employer payroll systems take the P45 figures at face value when adding a starter — that is the design intent. HMRC catches the discrepancy through Real Time Information once the new employer files an FPS, but the lag can run weeks or months. Tampered P45s used in fraudulent loan or housing applications meanwhile pass through HR and payroll undetected. HTPBE? inspects the P45 PDF at the moment of intake, before payroll trusts the numbers — standalone, no HMRC API, no payroll-bureau lookup.
What HTPBE? checks
Detection capabilities
Deterministic structural signals. No probabilistic scores, no model training.
Producer signature on the P45
Authentic P45s come from a UK payroll engine — Sage, IRIS, Brightpay, Moneysoft, Xero, QuickBooks Payroll, Moorepay, ADP UK. When the producer is Microsoft Excel, LibreOffice, Word, Chrome Headless, or a generic PDF library, the P45 was edited or fabricated on a desktop.
Incremental update trail
Edits to pay-to-date, tax-to-date, or tax code leave incremental updates in the xref chain. Authentic single-session payroll exports have one xref; tampered files have two or more.
Tax code and figures arithmetic
The relationship between gross pay, tax code, NI, and tax-to-date is checked. Edited figures break the chain in ways that spreadsheets routinely miss.
Modification timestamp gap
A real P45 issued on the leaving date has CreationDate ≈ ModDate. A months-later modification on a "freshly issued" P45 is a high-confidence flag for post-export editing.
Font subset divergence across pages
Multi-session edits or multi-source assembly leave font subset prefix shifts. Single-session legitimate exports have consistent subsets across all parts of the P45.
Text layer vs. raster layer mismatch
Replaced text in a rendered image leaves the underlying text layer untouched. The two layers stop agreeing — an immediate flag.
Share with engineering
Wire this into your intake pipeline in under a day
Two API calls — one POST to submit the PDF, one GET to retrieve the verdict. Forward this page to your engineering team; the full API reference, quotas, and copy-paste examples in cURL, JavaScript, Python, PHP, Go, and Ruby are one click away.
Pricing
Self-serve plans, no sales call
All plans include the same forensic checks. Pick the quota that matches your monthly document volume.
manualStarter
$15/mo
30 checks/mo
Manual spot-checks and integration testing
most commonGrowth
$149/mo
350 checks/mo
Active document processing pipelines
high volumePro
$499/mo
1,500 checks/mo
High-volume automation and API integrations
Enterprise (unlimited, on-premise available) — see full pricing
API key on signup. Free test environment on every plan. No card required.
Customer Stories
Teams that stopped document fraud
Compliance, finance, and risk teams use HTPBE? to catch manipulated PDFs before they become costly mistakes.
Caught an invoice where the total had been changed by less than a thousand dollars. Without this I would have approved it without a second look.
Sarah M.
AP Manager
United States
We had three applicants in the same week with bank statements that looked completely fine. Two of them were flagged as modified. You simply cannot see this by reading the document — it is in the file structure.
Lars V.
Risk Analyst, Online Lending
Netherlands
Salary slips were coming with altered figures. We identified two problematic files before the placement was finalised.
Priya K.
HR Operations Lead
India
Since we started checking documents this way, we stopped two applications early in the process that would have been very difficult to reverse later.
Julien R.
Fraud Analyst, Fintech
France
Some applicants were sending PDFs that looked authentic but had been edited in ways not visible to the eye. We now ask for checked originals when something is flagged. Already saved us from a few bad decisions.
Marta S.
Compliance Coordinator
Spain
One invoice was caught because there was a mismatch between the document dates and structure. That particular case would have cost us significantly.
Tariq A.
Finance Manager
United Arab Emirates
FAQ
Frequently asked questions
Does HTPBE? work with P45s from any UK payroll provider?
What if the previous employer is small and uses Word for P45s?
inconclusive with a producer-mismatch flag, prompting manual employer fraud detection.Can it catch P45s where only the tax code was edited?
modified with the incremental-update flag.Does the API need a reference original P45 to compare against?
What does an INCONCLUSIVE verdict mean for a P45?
Secure your workflow
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