Property appraisals and AI data leakage: what an appraisal report gives away in ChatGPT or Claude.

The appraisal report is the document that wins the listing, and it is written under time pressure by a sales agent who would like it to sound polished. That is why it ends up in ChatGPT or Claude: tighten this, make the tone warmer, check the comparable sales. It also holds more than a price. It records why the vendors are selling, what they hope to get, what the agent really thinks, the defects nobody has disclosed yet and the fees the agency will ask for. This page marks every sensitive item in a routine appraisal report and shows how the same report is written on Ermos inside the agency.

The property appraisal report

Prepared after the agent has inspected the property and before the vendors sign an agency agreement. The agency agreement that follows is regulated by the Property and Stock Agents Act 2002 and Regulation, and NSW Fair Trading says agents must act in their clients’ best interests at all times.

Market appraisal
Prepared for · 6 October 2026

The property. Federation house on 520 square metres with three bedrooms, one bathroom, the original kitchen and rear lane access. Walking distance to the station.

Why you are selling.

Our opinion of value.

Comparable sales.

Price expectations.

Condition.

Our proposal.

Your position.

An invented appraisal report. The agency, people and streets are fictional and the licence number is a placeholder. Hover or tap any highlighted item for the analysis; the full list is below.

What leaves the agency

  1. 1
    The vendors and their home address

    Two named people and the address of the home they live in. Personal information, and the key that ties everything below to them. Privacy Act guide.

  2. 2
    Reasons for selling and family detail

    A relative moving into aged care, a daughter’s name and town, and a retirement date. Personal information about the vendors and about third parties who are not clients. Privacy Act guide.

  3. 3
    The opinion of value

    The agent’s price range before any campaign. A professional judgement the agent has to stand behind, so an AI draft of it still needs checking by a person.

  4. 4
    Comparable sales

    Addresses and prices of recent sales. Sold prices are widely published, so little here depends on where it goes.

  5. 5
    The vendors’ price hopes and the agent’s candid view

    What the clients want and why the agent disagrees, including how the couple differs. NSW Fair Trading says agents must act in their clients’ best interests, honestly and fairly, and a candid view of a client is not written for anyone else. Privacy Act guide.

  6. 6
    Defects and unapproved work

    An unapproved deck and an out-of-date termite history, written plainly before they are packaged for buyers. Liabilities of the vendors that others will use.

  7. 7
    The proposed campaign, commission and marketing budget

    The agency’s terms for this client. Commercial information about the agency, and the start of the terms the agency agreement will have to set out.

  8. 8
    The vendors’ finances and timing

    No mortgage, an aged care deposit and a preference for an earlier settlement. Financial information that tells a buyer how much pressure the vendors are under. Privacy Act guide.

  9. 9
    The agent and the licence

    Ties the appraisal to a named agent and the licence the agency trades under.

What happens in Frontier Models (ChatGPT, Claude)

  • The whole document is transmitted to the provider’s servers. On personal plans the user cannot choose where it is stored or processed, and for the major providers that has generally meant outside Australia, under that country’s legal process. Some business plans offer storage in Australia, but the provider still receives the content.
  • On consumer tiers, prompts can be retained and used to train future models.
  • The provider’s staff and systems can reach the content under the provider’s own policies.
  • Once sent, the agency no longer controls it. Retention and deletion happen on the provider’s terms.

The same document on Ermos

Ermos Dominion

The document is drafted on a unit in your office, from your own templates and the property file. Every marked item stays on the unit, which keeps working with the internet switched off. Nothing in it is transmitted to an AI provider, so there is no disclosure to analyse: the confidentiality work is the same as for your file server.

Ermos Edge

Your documents, the index and your access boundaries stay on your own instance in an Australian data centre. When a staff member asks for this draft, only their question and the excerpts they are permitted to see go to a named Australian provider, who is contractually barred from keeping the content or training any model on it. Nothing is processed outside Australia.

Frontier Models (ChatGPT, Claude)Ermos EdgeErmos Dominion
Where the document is processedProvider servers, generally offshore on personal plansYour instance in an Australian data centre; answers generated in AustraliaThe unit in your office
Who can read itProvider staff and systems, under policyYour staff, within the boundaries you set. The named Australian provider processes only permitted excerpts, under contract, and keeps nothingYour staff only
Is it keptOn the provider’s termsKept on your instance; the provider is barred from retaining itStays on the unit
Can it train a modelOn consumer tiers, yesNo, by contractOnly your own unit learns from it, on your hardware

Part of AI data leakage in real estate agencies.

Common questions

Do ChatGPT and Claude use the information in a property appraisal report?
Anything pasted from the report goes to the AI company's servers and is processed there to produce a reply. As at October 2026, whether a conversation on a personal plan (ChatGPT Free, Plus or Pro; Claude Free, Pro or Max) can be used to train the models depends on a setting each user controls. Business plans (ChatGPT Business and Enterprise, Claude Team and Enterprise) and the developer APIs sit under commercial terms, and OpenAI and Anthropic each say they do not train on that content by default (OpenAI, Anthropic). On either product, the thumbs up and thumbs down buttons can send a whole conversation back for training. This report holds the Carmodys' reason for selling, Helen's mother's move into aged care, the $2.1 million they hope for and the agent's view that Helen is firmer on price than Ross.
Can we use ChatGPT or Claude for a property appraisal report if we remove the names?
No, because the detail still points to one couple. Removing names rarely makes a document anonymous. Information stays personal information while the person is reasonably identifiable, and the OAIC warns that information can be at risk of re-identification even when it has been de-identified or anonymised. A Federation house on 520 square metres in Summer Hill, a retirement from a dental practice in June and a move to Bowral to be near a daughter fit one household. The Office of the Australian Information Commissioner (OAIC) recommends in its guidance on commercially available AI products that organisations do not enter personal information, and particularly sensitive information, into publicly available generative AI tools, because of the significant and complex privacy risks.
Can ChatGPT or Claude be trusted to draft a property appraisal report?
Not without a check. Language models can produce fluent text with details that are not in the source, wrong figures, wrong dates or references that look real but are not. A qualified person should check every item against the file. In this report the opinion of value, the comparable sales, the 1.7 percent commission and the notes on the rear deck and the termite history would do the most harm if wrong, because the agent answers for them.
How can a real estate agency use AI for a property appraisal report without sending it to ChatGPT or Claude?
Ermos is built so the document stays under your control. On the Dominion AI unit it is drafted inside your office and none of it is sent to an AI provider. On Ermos Edge your documents and index stay on your own instance in an Australian data centre, and only the question and the excerpts the user is permitted to see go to a named Australian provider that is contractually barred from keeping them or training any model on them. The draft report is produced from the property file and the agency's own appraisal template. The sales agent checks the opinion of value and every comparable sale, then signs it.
Why is an appraisal report confidential when it ends up in marketing?
Because the report is written for the vendors and goes further than the listing. It records why they are selling, what they hope for, what the agent thinks of that, the defects and the fees. NSW Fair Trading says agents must act in their clients' best interests and honestly. A candid assessment of a client is written for the agency, so it belongs inside the agency.
Can an AI tool work out the price opinion?
It can draft one from comparable sales, but it cannot stand behind it. The opinion is the agent's judgement and the agent answers for it. The comparable sales are widely published, so the exposure is mainly in what the agent adds: the vendors' hopes, their circumstances and the defects.
Does the Privacy Act apply to the vendors' details in an appraisal?
They are personal information, and the family detail concerns people who are not clients. Whether the Act binds a particular agency depends on its turnover and activities: the OAIC says most small businesses with turnover of $3 million or less are outside it, subject to exceptions such as operating a residential tenancy database or trading in personal information. A small agency that is an AML/CTF reporting entity is covered only for its AML/CTF activities.

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AI data leakage in real estate agencies Resources The Privacy Act, the APPs and AI All professions