In short

A long-held shareholding, especially with reinvested dividends, is really many separate parcels, each with its own purchase date and cost base. If your records can identify which parcel you're selling — statements, certificates, registry history — the ATO accepts your selection. If you can't identify them, first-in-first-out is imposed instead, so record-keeping done years earlier decides whether you have a real choice.

Your holding statement shows one line: a company name and a number of shares. It looks like one asset.

It usually isn't. If you bought that holding across several purchases over the years — and especially if you've been reinvesting dividends — you own a stack of separate parcels, each with its own purchase date and its own cost base. And when you sell part of the holding, you're not selling an abstract slice of it. You're disposing of particular parcels.

Which matters, because you generally get to choose which ones — provided you can prove which ones they were. This article is general information only and it is emphatically not tax advice; this is an area where the right answer depends on your whole return, and it's worth an accountant's time.

Is it out of your hands? Not unless your records let it be

The common belief is that it works on first-in-first-out: the oldest shares go first, automatically, and there's nothing to decide.

That isn't the starting position in Australia, but the correction has a condition attached, and the condition is the whole game. The ATO's guidance is that where you have the relevant records — a CHESS holding statement, an issuer sponsored statement, share certificates — "you can select which shares you have sold and identify their cost," and that in other cases "the Commissioner will accept your selection of the identity of shares disposed of" (Australian Taxation Office, https://www.ato.gov.au/forms-and-instructions/capital-gains-tax-guide-2021/whats-new/investments-in-shares-and-units/identifying-shares-or-units-sold, as at August 2026).

Now the part the popular belief gets half-right. Where a taxpayer maintains appropriate records, specific identification is the method used; but where the taxpayer is unable to identify the shares, first-in-first-out is required (ATO). So FIFO isn't the default rule people imagine — it's the fallback imposed when your paperwork can't support anything better. The choice is real, and it is bought and paid for by record-keeping done years earlier.

The consequence is the whole point of this article: this is a decision, it has a price attached, and whether you get to make it at all was settled long before you decided to sell.

What does the choice actually change?

Four things, and they don't always point the same way.

Your cost base. A parcel bought three years ago at a high price produces a much smaller gain — possibly a loss — than one bought in 1994 for a fraction of today's price. Same company, same share price today, wildly different tax outcome.

Whether the discount applies. The CGT discount depends on how long that parcel was held, not how long you've owned shares in the company generally. A recently acquired parcel may not qualify at all. Our article on the CGT discount and the 12-month rule sets out how it works.

Which calculation methods are open to you. For assets acquired a long time ago there can be more than one way of working out the gain, which compounds with the parcel choice. Our article on the indexation method versus the discount for pre-1999 assets covers that.

Whether you realise a gain or a loss at all — which becomes important if you're carrying losses forward, and we'll come back to that.

Why isn't "sell the highest cost base" the answer?

The instinctive rule is to pick the parcel that cost the most, so this year's gain is smallest. It's often sensible. It is not a rule, and treating it as one gets people into trouble.

It can leave you holding nothing but very-low-cost-base parcels — you haven't solved the problem, you've concentrated it, and someone deals with it later, possibly your estate. A discount-eligible parcel can produce a better result than a higher-cost-base parcel that doesn't qualify. And if you actually want a realised gain this year, because your income is unusually low or you have losses to absorb, the whole calculation inverts.

So I'm deliberately not giving you a rule of thumb. What I'd say instead is that this is arithmetic with several inputs, an accountant does it in a few minutes, and almost nobody does it well from memory in the week they're selling.

What is the retirement angle?

Three things make this more consequential in retirement than it was during your working life.

The low-income window. Many people have a genuine gap — employment income has stopped, and pension income is modest or hasn't started. Realising a gain in a year like that is a very different proposition from realising it while you were working. Our articles on the effective tax position of self-funded retirees and on franking credits and imputation cover the wider picture your gain lands in.

Losses die with you, and the ATO says so plainly. If the deceased had any unapplied net capital losses when they died, those losses "cannot be passed on to you as the beneficiary or legal personal representative" to offset against your own net capital gains — and they can't be used against the deceased estate's gains either (Australian Taxation Office, https://www.ato.gov.au/forms-and-instructions/capital-gains-tax-guide-2019/part-a-about-capital-gains-tax/deceased-estates/unapplied-net-capital-losses, as at August 2026). For someone sitting on unused losses and unrealised gains, that is a genuine argument for acting in your lifetime rather than leaving it, and most people have never been told it. Our article on capital losses extinguishing on death covers the detail.

The Age Pension interaction isn't what people assume. How a capital gain is treated for the income test surprises almost everyone, and separately the sale proceeds become assessable assets once they're sitting in your account. Our articles on capital gains and the Age Pension income test and on Age Pension asset categories set out both, and I'd read them before selling rather than after.

What decides whether you have a choice at all?

Records. As above — without them, FIFO is imposed rather than chosen.

You can only identify a parcel if you can prove it exists, and this is where thirty years of dividend reinvestment does its damage: every reinvestment is its own small parcel, with its own date and its own price. A single line on a statement can be forty or a hundred parcels, and the plan statements have often long since gone. Our article on dividend reinvestment plans in retirement covers the mechanics.

It gets more layered from there. Bonus issues, returns of capital, consolidations and demergers all adjust cost bases — our article on bonus shares, returns of capital and consolidations goes through them. Inherited shares carry their own acquisition history, covered in our articles on the cost base of inherited assets and on the inherited asset rules for beneficiaries.

There is one genuinely useful reconstruction tool most people don't know about. Share, stapled security and unit transaction data reported to the ATO by third parties can be viewed and downloaded through ATO online services: sign in to myGov, go to the ATO, and select Shares and unit records, then choose a date range and download (Australian Taxation Office, https://www.ato.gov.au/online-services/online-services-for-individuals-and-sole-traders/ato-online-services-and-mygov/using-ato-online-services/your-securities-records-in-ato-online, as at August 2026). The download may even include a summary CGT calculation, though only for disposals where a cost base could be calculated. Read the ATO's own caution before leaning on it: you "must not rely only on the information in these records and must review your own records to verify that the information is complete and correct" (ATO). It is a starting point for reconstruction, not a substitute for your paperwork.

The practical instruction, then: reconstruct your records before you need them, not in the week you're selling. Share registries, old tax returns and the ATO download can all help, and none of them should be assumed complete. Our article on how long to keep tax records covers what to hold onto, and our article on ATO data matching for retirees explains what the ATO already sees — because share disposals are reported to it by third parties regardless of what you can prove (ATO, https://www.ato.gov.au/businesses-and-organisations/preparing-lodging-and-paying/third-party-reporting/reporting-of-shares-and-units-transactions).

What do the worked examples show?

Two illustrations of what the records decide. Both are illustrative only and not tax advice; the right parcel depends on your entire return and is a question for your accountant.

Consider Robert, 69, a self-funded retiree who has held shares in one company since 1996 and reinvested every dividend since. He needs about $40,000 and plans to sell roughly a fifth of the holding. Because he kept his issuer sponsored statements and the DRP advices, he can identify particular parcels and select which he is disposing of, and the Commissioner will accept that selection (ATO). That lets his accountant compare a high-cost-base parcel bought near a market peak against an older parcel that qualifies for the discount, and choose on the arithmetic rather than by default. On these facts, doing the comparison before the sale is generally rational, because after the sale the choice has already been made by whatever the paperwork supports.

Now consider Helen, 73, in the same position with the same company and a similar holding — except the DRP statements went out in a house move a decade ago and the registry can only supply part of the history. Unable to identify the shares, she is required to use first-in-first-out (ATO), which means the oldest and almost certainly lowest-cost-base parcels are treated as sold first, producing the largest gain the facts allow. Nothing improper has happened and no election was made against her; the fallback simply applied. On these facts, the useful step is the one available to anyone still holding shares they haven't yet sold: start the reconstruction now — registry history, old returns, and the ATO's Shares and unit records download — so the choice exists when it's needed.

Where does this not apply the same way?

If you're classed as a share trader rather than an investor, the framework is different — our article on trader versus investor status for retirees explains the distinction, which is not a matter of choice.

And shares held inside your super fund aren't yours personally; they're the fund's assets, under an entirely different tax regime. Nothing above applies to them in the same way.

Sources

Key takeaways

  • A single shareholding built up over years, especially through dividend reinvestment, is really made up of many separate parcels, each with its own purchase date and cost base.
  • If your records identify which parcel you're selling, the ATO will accept your selection; if you can't identify them, first-in-first-out is imposed as the fallback.
  • Which parcel you choose affects your cost base, whether the CGT discount applies (based on that parcel's own holding period), which calculation methods are available, and whether you realise a gain or a loss at all.
  • Unapplied capital losses die with the deceased and can't be passed to a beneficiary or the estate — a reason to consider realising gains against them during your lifetime rather than leaving it.
  • ATO online services has a Shares and unit records feature that can help reconstruct history from third-party reporting, but the ATO itself warns not to rely on it alone — verify against your own records.

Frequently asked questions

Can I choose which shares to sell for tax purposes?

Yes, but only if your records let you identify specific parcels — statements, certificates, or reconstructed registry history. Where you have appropriate records, the Commissioner will accept your selection of which shares were disposed of. Where you can't identify them, first-in-first-out (FIFO) is imposed instead, treating the oldest shares as sold first.

Why does it matter which share parcel I sell?

Different parcels can have very different cost bases depending on when they were bought, which changes the size of your gain or loss. The CGT discount also depends on how long that specific parcel was held, not how long you've owned the company generally, so a recently acquired parcel may not qualify while an older one does.

What happens to unused capital losses when someone dies?

They die with the person. Unapplied net capital losses cannot be passed to a beneficiary or legal personal representative to offset their own gains, and can't be used against the deceased estate's gains either. This is a reason to consider realising gains against carried-forward losses during your lifetime rather than leaving them unused.

How can I reconstruct my share purchase history if I've lost the records?

ATO online services has a Shares and unit records feature (accessed via myGov) that shows share and unit transaction data reported to the ATO by third parties, and can even include a summary CGT calculation. The ATO itself cautions not to rely on this alone — verify it against your own records, since it may be incomplete.

A note on advice. This article is general information only and doesn't account for your personal circumstances. Everyone's situation is different — before acting, it's worth talking it through with a licensed adviser who knows your full picture.