The ATO is asking about a rental property I sold years ago — how does it know, and can I still fix it?

The sale was three years ago. The loan was paid out at settlement, the agent's commission came off the same statement, and what was left went into the next thing. It stopped being a live subject a long time ago.

Then something turns up in myGov naming a property, a date and one particular year's tax return, and asking you to check whether the capital gain was reported correctly. Nothing has been decided at that point — you are being asked to look. The reasonable first question is where the ATO got the sale from.

The ATO has its own copy of the transfer

The real property transactions data-matching program has run since 2005, and the ATO states its purpose plainly: compliance with tax obligations on the disposal of real property, especially in relation to capital gains tax. The data comes from state and territory revenue offices and land titles authorities, obtained under the formal information-gathering power in section 353-10 of Schedule 1 to the Taxation Administration Act 1953 — a coercive power, meaning providers are obliged to hand it over.

The fields are the ones that decide a CGT calculation: the sale contract date, the settlement date, the address, the total transfer price, and each party's ownership percentage and manner of holding. The ATO says it matched records for over 2 million individuals each financial year under this program, and that in 2016–17 it identified over 5,431 cases where real property dealings were not treated correctly, raising an additional $65 million.

Two dates explain the reach. Transfers occurring after 1 July 2017 are reported to the ATO under a legislative regime rather than collected program by program. And the program data runs back to 20 September 1985, the start of the CGT regime, because a cost base can require a property's whole ownership history, not just its sale.

The year it belongs in is set by the contract, not the settlement

This is the most common reason a return and the ATO's record point at different years. When you sell a rental property, the time of the event — the point at which you make a capital gain or loss — is when you enter into the contract, not when you settle. A contract signed in June that settles in November belongs in the earlier income year, and a return prepared around the date the money landed will have put it in the later one.

The second common gap is the cost base: the purchase price, plus incidental costs of acquiring, holding and disposing such as conveyancing, stamp duty and agent's commission, plus capital improvements. It does not include amounts you have claimed or could claim as a deduction, so capital works and decline in value deductions claimed across the rental years come back off the cost base at the end. That subtraction is how a sale the owner remembers as barely breaking even still produces a taxable gain. For co-owners, each gain or loss follows the ownership interest; where the property was held at least 12 months, the 50% discount applies to the gain.

What the amendment time limits actually say

Individuals generally have 2 years to amend an assessment, running from the day after the notice of assessment is sent. For sole traders it is 2 years for 2023–24 and earlier years, and 4 years from 2024–25 onwards. Past that point an amendment request is replaced by an objection, and an extension of time to object can be requested in some circumstances.

The limit running the other way sits on the same ATO page: generally the ATO cannot amend an assessment more than 2 years after it was issued unless you request it — but it may amend outside the time limit in exceptional circumstances, such as where evasion or fraud has occurred. That sentence is why a letter about a sale from four years ago is not automatically a letter about nothing.

Coming forward first is worth a specific amount

The ATO's published position on voluntary disclosures is not vague. It will reduce some penalties by 80% where you disclose a shortfall amount before the earlier of the day it tells you it is going to examine your affairs, or the last day it will accept disclosures where it has publicly asked for them. If the shortfall is under $1,000 and you come forward before being notified of an examination, the penalty is reduced to nil. After notification the reduction drops to 20%, and only where the disclosure can reasonably be estimated to have saved the ATO significant time or resources.

A shortfall also attracts an interest charge, which the ATO may reduce where it results from an unprompted disclosure made outside any examination — you may have to ask for that and support it. Interest is the part worth moving on, because since 1 July 2025 the general interest charge is no longer deductible.

Two things commonly got wrong

The first: "it has been more than two years, so that year is closed." The two-year rule limits when the ATO can amend an assessment on its own initiative, and it carries an express exception for evasion or fraud. It is also not what a review letter is usually doing — the letter asks you to check and correct your own return.

The second: "it sold for less than we paid, so there was nothing to report." A capital loss still belongs in the return for the year of the contract; that is how it is carried forward and deducted against capital gains in later years. Leaving it out does not keep the year quiet, and it throws away the loss.

This is general information current as at 31 August 2026, not advice about a particular sale — outcomes turn on whether the property was ever a main residence, who was on the title and in what shares, and what was claimed while it was rented.

If a letter has arrived, the useful work is documentary and can be done before anything is answered: the purchase contract with its stamp duty and legal costs, the sale contract with its date, both settlement statements, invoices for capital improvements, and the depreciation and capital works claimed in each year's return. Those settle the year and most of the number. Our earlier pieces on the clearance certificate and the 15% withheld at settlement, and on how a gain is calculated for assets held before 1 July 2027, cover the neighbouring questions. Property investor tax is one of our four service areas, and the investment property calculator on this site is there while you pull the file together.