Main Residence CGT Exemption Calculator (Australia)

What the main residence exemption calculator does

The main residence exemption calculator shows how much of the gain on an Australian home escapes capital gains tax when the property was not your main residence for the whole ownership period, and prices the tax on whatever is left over. It counts your exempt days, applies the six-year absence rule to any period the home was rented out, apportions the gain, applies capital losses in the correct order, applies the CGT discount where the holding period allows it, and taxes the remainder on top of your other income at the resident rates plus the Medicare levy.

Most home sales in Australia never touch a tax return. The ones that do are almost always partial exemption cases: a first home that became an investment, a job transfer that turned into five years interstate, a couple who kept the old unit rented while paying off the new house. Those are the cases this tool is built for.

The day-count method, in full

The ATO does not care which years the growth happened in. It cares how many days the dwelling was your main residence. The formula is the gross capital gain multiplied by the days the dwelling was not your main residence, divided by the total days of ownership.

That means a property that doubled in the two years you lived there and flatlined for the eight years it was rented is still taxed on eighty per cent of the gain. Value timing is irrelevant; day counts are everything. It also means small changes to the dates matter. Counting from settlement instead of contract, or forgetting a few months of vacancy between tenants, moves the answer.

Enter the ownership period in days rather than years, because that is how the calculation is actually run and because part-years are where the errors creep in. Twelve years is 4,380 days at 365 days a year; use the real day counts from your contracts if you have them.

The six-year absence rule, and its limits

Section 118-145 lets you keep treating a former home as your main residence after you move out. Two versions apply.

If the dwelling produces income while you are away, the choice lasts a maximum of six years. That is the figure this calculator caps your rental absence days at, and it is held as a parameter rather than written into the code, so it tracks the law rather than the day the tool was built.

If the dwelling produces no income, the choice can be made indefinitely. A home left vacant, lent to family rent free, or used only by you on visits falls into this category. Enter those days separately, because they are not capped.

Three limits deserve attention. First, the dwelling must have been established as your main residence before you moved out; you cannot apply the absence rule to a property you never lived in. Second, the six years run from each departure, so moving back in and re-establishing the home resets the clock and a fresh six-year period becomes available. Third, the choice is exclusive: while you apply it to the old home, the home you actually live in is not exempt for those same days.

Losses, the discount, and the order of operations

The order the ATO applies is fixed, and getting it backwards costs money.

• work out the gross gain: proceeds less the cost base and the incidental costs of selling
• apportion it by days to find the assessable part
• reduce the assessable part by capital losses, current year first and then carried forward
• apply the CGT discount to whatever is left, if the property was owned for more than twelve months
• add the discounted amount to your other taxable income for the year

Losses come off before the discount, never after. A fifty thousand dollar loss shelters fifty thousand dollars of gain if applied first, and only twenty five thousand of value if applied after halving. The discount itself requires more than twelve months of ownership, which in practice means at least 366 days between the acquisition contract and the sale contract.

Because the taxable gain is stacked on your other income, the tax on it depends entirely on what else you earned that year. A gain of forty thousand dollars costs far less to someone on a modest salary than to someone already in the top bracket, which is why the calculator asks for your other taxable income and runs the whole amount through the brackets, the low income tax offset and the Medicare levy rather than assuming a flat rate.

Getting the cost base right

The cost base is more than the purchase price. It includes stamp duty, conveyancing, buyer's agent fees, and the capital improvements you made along the way, a new kitchen, a deck, a subdivision cost. The incidental costs of selling, principally agent commission and legal fees, are entered separately here so you can see their effect.

Two adjustments catch people out. Capital works deductions claimed while the property was rented reduce the cost base, so a decade of claiming 2.5 per cent depreciation on the building makes the eventual gain larger than the purchase and sale prices suggest. And holding costs such as interest, rates and insurance can only sit in the cost base for periods when they were not deductible, which for a rented property means they generally cannot.

If the home was your main residence first and you later rented it out, the home first used to produce income rule usually applies. You are treated as having bought it at market value on the day it first earned rent, and the day count starts from that date. Where that rule applies, enter the market value as the cost base and count ownership from that day; the partial exemption apportionment then runs over the shorter period.

Foreign residents and other traps

Since 30 June 2020 a person who is a foreign resident for tax purposes at the moment of the sale generally gets no main residence exemption at all, regardless of how many years they lived in the property. Narrow life-events exceptions exist for a short absence involving terminal illness, death, or a marriage breakdown. The consequences are severe enough that anyone selling while overseas should confirm their residency position before signing a contract, not after.

Other situations that change the answer include running a business from home, which brings an interest-deductibility apportionment into play; land over two hectares, where only the dwelling and adjacent land within the limit are covered; and inherited dwellings, which have their own two-year disposal window. This calculator handles the mainstream partial exemption case and does not model those.

Reading your result

The exempt share of the ownership period tells you how much of the gain never enters the tax system. The absence days beyond the cap tell you how much of your rental period fell outside the six-year rule, which is the single figure that most often surprises owners of long-term rentals. The taxable gain is the amount added to your income, and the tax as a share of the gross gain shows the real cost as a percentage of everything you made.

If the days beyond the cap are large, it is worth checking whether you ever moved back in during that period, because a genuine return resets the six-year clock and can pull thousands of days back inside the exemption.

This is an estimate based on the day counts and figures you enter and the current ATO parameters, not personal tax advice. Property CGT depends on contract dates, cost base adjustments, residency status and the choices you make in your return, so confirm the outcome with a registered tax agent before relying on it.

About This Tool: Main Residence Exemption

Main residence exemption: use this tool to get an instant, accurate estimate. The figures follow official ATO guidance and every rate and threshold is kept up to date for 2026. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.