# Detect tampered and deepfake Contract > Proving a contract was altered after signing means locating the edit in the file rather than arguing about what was agreed. The changes that matter are small: a payment term moved from 60 days to 30, a clause slipped into an otherwise untouched page, an inner page reprinted while the genuine signature page stays exactly where it was. None of that shows on the printed page, and all of it leaves structure behind. TamperCheck reads the structure and names the page that moved. **Canonical URL:** https://tampercheck.ai/documents-support/contract **API document class:** `contract` **Last updated:** 2026-10-07 --- ## What a genuine contract contains An executed contract names the parties and the capacity in which each one signs, recites what the agreement covers, and then sets out numbered clauses: obligations, payment terms and amounts, term and termination, liability and indemnity, governing law and jurisdiction. Schedules and annexures are attached at the back and referenced from the body. The execution block at the foot holds each signatory's name, title, signature, and date of signing, with witness or company-seal blocks where the jurisdiction requires them. Pages are numbered as a count and initialled in the margin. Those elements police one another. A footer that reads page 4 of 22 fixes how long the signed document was, and margin initials tie each page to the people who signed the last one. Numbered clauses cross-reference each other, so a subclause inserted at 7.3 leaves the reference in 11.2 pointing at the wrong text. Payment figures normally appear twice, once in the body and once in a payment schedule. The execution date must sit at or after the dates recited in the opening paragraphs. Editing one of these contradicts another. ## How contract forgeries are made ### Page substitution The signature page is genuine and stays where it is while an inner page is reprinted with different wording and slotted back into the bundle. Because no signature was touched, the result survives a visual review. The substituted page rarely shares the compression history, margin geometry, or text rendering of the pages either side of it. ### Clause insertion A clause or subclause is added to an executed agreement, usually one granting a right or capping a liability that was never negotiated. Inserting text reflows everything below it, so line spacing shifts, numbering runs on, and any cross-reference elsewhere in the contract that points past the insertion no longer resolves to the clause it was written for. ### Payment term edits An amount, a rate, or a due period is changed in the body while the payment schedule at the back is left alone, or the other way round. This is the most common commercial edit because it is the one worth money, and the two statements of the same figure almost never get updated together. ### Signature transplant from another agreement A counterparty signature is lifted from a document they really did sign and dropped onto one they never saw. The transplanted mark carries its own paper tone, edge halo, and resolution, and those travel with it onto a page that was captured under different conditions. ### Execution date changes The date in the signature block is moved so an agreement appears to predate the event it was actually written to cover: a claim, a competing deal, an insolvency. The printed date changes in seconds. The dates recited in the opening paragraphs and the timestamps carried inside the file do not follow it. ### Agreements that were never executed Some disputed contracts were drafted or generated from scratch and signed by nobody. They are internally consistent, so clause cross-references and payment figures agree, and they are identified instead by uniform text rendering across pages that should have been printed and scanned, and by signatures with no capture artefacts at all. ## What TamperCheck checks on a contract TamperCheck runs 200+ forensic checks across three layers and returns a risk score from 0 to 100 with plain-English findings tied to specific regions of the document. These three carry the most weight on this document class. ### Signature forgery analysis Signature regions are assessed for ink consistency and for how the stroke sits on the page, which distinguishes a genuine pen stroke from a pasted image of one. ### Reference and document number checks Document, account, and reference numbers are checked for issuer format conformance and against every other place the same value appears on the page. ### Field-level forensics Every text region is analysed in its own right rather than as part of one whole-page image. This catches the smoothed and feathered edits that whole-image Error Level Analysis misses entirely. ### And many more checks The three above are the layers that carry the most weight on a contract. Every upload runs the full suite of 200+ checks regardless of document class, spanning file structure and metadata, pixel-level forensics, font and text rendering, optical and print characteristics, provenance signals, AI-generation signatures, and many more checks. ## Who verifies a contract, and why Legal teams and vendors resolving disputes over executed agreements. In each case the document is being used to unlock money, access, or a legal status, which is exactly what makes it worth forging. ## How to verify a contract in 4 steps 1. **Check the fields against each other.** Read payment terms, clause insertions, and counterparty signature together rather than one at a time. Forgers typically change one value and leave the rest of the document describing the original. 2. **Inspect the file metadata.** Open the document properties and look at the producer, creation date, and modification date. A document produced by a consumer PDF editor, or created long after the date printed on its face, is worth a closer look. 3. **Ask for a second document.** Request a corroborating document from the same issuer or an adjacent period. Forgery effort concentrates on one file, so inconsistencies surface as soon as there are two to compare. 4. **Run a forensic check.** Manual review catches obvious edits but not field-level pixel manipulation or synthetic generation. TamperCheck runs 200+ forensic checks on a contract and returns a risk score from 0 to 100 within seconds, at $0.50 per document. ## Frequently asked questions ### How do I prove a contract was altered after signing? You prove it from the file's own internal evidence rather than from recollection: the page count in the footer, the initials in the margin, the compression profile of each page against its neighbours, and the clause cross-references. A page reprinted after execution does not match the pages around it, and an inserted clause leaves references elsewhere pointing at the wrong text. TamperCheck returns findings tied to the specific region that changed. ### How can you tell if a contract has been edited? The clearest signals are contradictions the editor did not think to fix: a payment figure in the body that disagrees with the payment schedule, a clause number quoted elsewhere that now resolves to different wording, or a page whose margins and font rendering differ from those on either side. A competently edited PDF gives none of that away visually, which is why review by eye keeps missing it. ### Can you detect a swapped page in a signed PDF? Yes. A page regenerated and slotted back into a scanned bundle carries a different history from its neighbours: different compression, different noise floor, sometimes selectable text on one page where the rest of the document is an image. Per-page analysis compares each page against the others in the same document and flags the one that does not belong. ### Does scanning or printing a contract hide an edit? No. Printing and rescanning removes some traces and creates others, because the page that was edited went through an extra rendering step that the pages around it did not. Its text sits on a different baseline grid, its ink density differs, and its noise characteristics separate from the rest of the bundle under analysis. ### What does a forensic contract check actually look at? It runs 200+ forensic checks across the document and returns a risk score from 0 to 100 with the findings attached to regions of specific pages: signature blocks, clause bodies, schedule attachments, page numbering, and the boundaries where one page was captured differently from another. A verdict comes back within seconds, at $0.50 per document. ## Related document types - Affidavit: https://tampercheck.ai/documents-support/affidavit - Court Order: https://tampercheck.ai/documents-support/court_order - Legal Notice: https://tampercheck.ai/documents-support/legal_notice - Power of Attorney: https://tampercheck.ai/documents-support/power_of_attorney - Notarised Document: https://tampercheck.ai/documents-support/notarised_document - Declaration: https://tampercheck.ai/documents-support/declaration --- Try TamperCheck now: https://tampercheck.ai/dashboard · Docs: https://tampercheck.ai/docs · Pricing: https://tampercheck.ai/pricing