AI data leakage in real estate: what leaves when property files go into ChatGPT or Claude.

A real estate agency holds two kinds of file. The sales side holds vendors and buyers: why they are selling, what they can borrow and what they will pay. The property management side holds tenants and owners: identity documents, employers, bank statements, arrears, and sometimes the reason a tenant is leaving a relationship. NSW agents act under the Property and Stock Agents Act 2002, must act in their clients’ best interests, and face strict rules on tenancy databases under the Residential Tenancies Act 2010. Whether the Privacy Act applies depends on the agency’s turnover and activities, and agencies that broker sales are now within the AML/CTF regime. This series marks up ten documents and shows where each item goes when the document is pasted into ChatGPT or Claude.

The documents, one at a time

Report or memoThe property appraisal report

Why the vendors are selling, what they hope for, what the agent really thinks and the defects not yet disclosed.

See what leaves → AgreementThe sales agency agreement

Identity checks, the price estimate, commission, rebates, a health request and the account the money goes to.

See what leaves → FormThe rental application form

Identity documents, birth dates, income, bank statements, a guarantor and a reason for moving, on one form.

See what leaves → SpreadsheetThe rent roll spreadsheet

Every tenant, every arrear, every owner and the bank account the rent is paid into. One row per property.

See what leaves → EmailThe buyer offer email to a vendor

The offer, the buyers’ finance and circumstances, the other buyers and the agent’s advice, in one email.

See what leaves → EmailThe vendor update email

Named buyers and their feedback, the offers, a pest report, the reserve and the vendors’ own circumstances.

See what leaves → Report or memoThe routine inspection and condition report

Who lives there, the key safe code, defects, photos of private belongings and the property manager’s impressions.

See what leaves → SpreadsheetThe buyer register spreadsheet

Names and mobiles against budgets, finance status and notes about separations, illness and family money.

See what leaves → Text or chat messageThe landlord and tenant text messages

An owner who wants a tenant listed, a tenant in difficulty, a safety disclosure and a staff mistake, in one thread.

See what leaves → LetterThe tenant complaint response letter

The complaint, the agency’s admission, the staff action, the tenant’s arrears and safety and the remedy.

See what leaves →

How the leakage happens

The mechanism is the same for every document. The whole text 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. On consumer tiers it can be retained and used to train future models. The provider’s staff and systems can reach it under the provider’s own policies. Once sent, the agency no longer controls it. Our on-premise vs cloud comparison sets out the four ways to run AI and where each one puts your documents.

The obligations in play

Each marked item on these pages links to the guide that covers its obligation:

The same documents on Ermos

Ermos Dominion drafts and searches on a unit in your office, so the documents never leave it. Ermos Edge keeps your documents on your own instance in an Australian data centre and sends only permitted excerpts, per question, to a named Australian provider. Every page in this series ends with both, item by item.

Common questions

Can real estate agents use ChatGPT or Claude with client information?
Only with care, because the duties to clients and the Privacy Act both stay in play. 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. NSW Fair Trading says agents must act in their clients' best interests, honestly, fairly and professionally, and that duty sits with the agent whichever tool drafts the document. The OAIC says businesses with turnover of $3 million or less are generally outside the Privacy Act, but an operator of a residential tenancy database is covered whatever its turnover. A small agency that is an AML/CTF reporting entity is covered only for its AML/CTF activities.
Do ChatGPT and Claude train on what staff paste in?
It depends on the account each person is using. 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. For a real estate agency the question matters because one paste of a rent roll or a tenant application can carry tenants' arrears, identity documents and owners' bank details.
Do business plans such as ChatGPT Business or Claude Team solve the problem for real estate agents?
Only in part. A business plan changes the default on training, but it does not change who receives the content. On a personal plan the user cannot choose where conversations are stored or processed. Some business plans let an organisation choose to store data at rest in Australia (OpenAI), which still leaves the content with the AI company. The OAIC's guidance also tells organisations to review carefully the terms and settings that will apply to their use of any AI product. For an agency, the open question is whether vendors, buyers, tenants and owners agreed to their details going to that AI company. Our comparisons with ChatGPT Enterprise and Claude weigh the trade-offs.
What is the safest way for a real estate agency to use AI with client documents?
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. For a real estate agency, staying in control means the files of vendors, buyers, tenants and owners stay where the agency can answer for them.
What is AI data leakage in a real estate agency?
Client information leaving the agency's control through an AI tool. When an appraisal, a tenant application or a rent roll is pasted into ChatGPT or Claude it is sent to the provider's servers, can be kept on the provider's terms, can be used to train future models on consumer tiers, and can be reached by the provider's staff and systems. For an agency that means vendors, buyers, tenants and owners.
Does the Privacy Act apply to a small real estate agency?
Not always. The OAIC says most small businesses with turnover of $3 million or less are outside the Act. The exemption does not apply to an operator of a residential tenancy database or a business trading in personal information. A small business that is a reporting entity under the AML/CTF Act is covered only for its AML/CTF activities. AUSTRAC lists brokering the sale of real estate as a designated service from 1 July 2026, so an agency doing that should check its position.
Which agency documents carry the most risk?
The rent roll, because it puts tenants' arrears next to owners' bank details; the tenant application, because it holds identity documents, income and bank statements; and the buyer register, because it records budgets, finance and personal circumstances. Appraisals and vendor emails follow, since they hold what a vendor will accept. The pages in this series take each one in turn.

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