A cost base is only as good as the records behind it. Each of the five cost-base elements needs its own paper trail — and when you eventually sell, the ATO looks for evidence, not estimates. This is the practical checklist of what to keep, why, and for how long, plus what a contemporaneous record looks like next to a reconstructed one. General information only, not tax advice — confirm with your accountant.
Records readiness — tick what you have#
Tick every record you can already put your hands on.
What to keep, element by element#
| Cost-base element | Keep these records | Why |
|---|---|---|
| 1 — Acquisition | Contract of sale, settlement statement, proof of what you paid (and the market value of anything non-cash you gave) | Fixes your starting figure — the single largest number in most cost bases |
| 2 — Incidental | Stamp/transfer duty notice, conveyancer and legal invoices, agent’s commission, valuer/surveyor fees, advertising and search costs | Each is a separately claimable cost — but only if you can produce the invoice |
| 3 — Ownership | Rates and land-tax notices, loan interest statements, insurance premiums, maintenance invoices — flagged for the periods they were not tax-deducted | Only the un-deducted portion counts; you need to show which periods those were |
| 4 — Capital improvements | Builder and trade invoices, council approvals, before/after dates, and photos | Proves the work was capital (not a deducted repair) and that it is still reflected in the property |
| 5 — Title preservation | Legal invoices and correspondence for defending or establishing title | Links the spend to protecting your ownership, not to earning income |
Organised records make either evidence path stronger — the dated valuation and the Treasurer’s free apportioning method both rely on you being able to substantiate the elements.
How long to keep them#
The rule of thumb is to keep records that relate to a CGT event for five years after the event — that is, five years after you sell. Because a property sale can be decades after you buy, in practice that means keeping your purchase and improvement records for the whole time you own the property, plus five years afterwards. If you make a capital loss and carry it forward, keep the records until five years after the year you finally use the loss. When in doubt, keep it — storage is cheap; a disallowed cost is not.
Contemporaneous vs reconstructed records#
To the ATO, when a record was created matters as much as what it says.
A dated invoice, a settlement statement, a bank record, a valuation signed as at the relevant date. It was made when the event happened, so it is hard to dispute and easy to rely on. This is the strongest evidence.
An estimate you assemble years afterwards — "the reno was about $80k", a figure worked back from a later sale, a value guessed for a past date. It may be accepted, but it carries less weight and is easier to challenge.
This is the honest case for acting around the date rather than long after it: a value captured close to 1 July 2027, while the market evidence is fresh, is easier to gather and more defensible than a figure reconstructed years later when you finally sell. It is not about rushing — it is about the quality of the evidence.
The 1 July 2027 record you can’t recreate#
The reset makes the market value at the end of 30 June 2027 the new starting point for future gains, so it becomes one of your most important cost-base records. Setting that value is elective: the ATO will offer a free apportionment formula as the alternative, so a valuation is never compulsory — it is a choice with evidence trade-offs. A dated, independent valuation prepared to be ATO-acceptable is simply a contemporaneous record of the one figure you cannot easily reconstruct later. The worked examples show, in dollars, when that extra evidence changes the tax result — and when the free formula is close enough.
Turn your records into evidence#
- Not sure what each element covers? Start with how to calculate your CGT cost base.
- See the reset in three scenarios — the worked examples.
- Want a dated value as at the end of 30 June 2027? For a signed valuation prepared to be ATO-acceptable, choose on-site (full inspection) from $690 (a valuation done later is retrospective, quoted separately). A fixed-price desktop is $299 (unit) / $349 (house), complex properties from $399, but with no inspection it gives an indicative value only — for monitoring or updating an earlier figure, not a CGT cost base. Reserve at CGT Valuation Ready, an independent valuation service.
- Accountants organising records across a client book can use wholesale volume pricing and batch submission at the Valuation Ready partner portal.
Register interest#
We use your details to prepare your valuation and to contact you about it. If you engage us, we also create and keep a long-term record of the property's documents and condition as at 30 June 2027, so that you, your accountant, or a valuer you appoint can use it when the property is eventually sold; and we keep property information after your personal details are removed, to improve our valuation reference data. See our privacy policy; you can ask us to delete your details at any time.
Common questions#
What records do I need for CGT on a property?
How long do I have to keep CGT records?
What is a contemporaneous record?
I've lost my purchase invoices — what can I do?
Do I need to keep records for the 1 July 2027 value?
Can I include rates and interest I already claimed as deductions?
General information only — not tax, financial or legal advice. Any indicative appraisal is automated and is not a certified or ATO-suitable valuation; the signed valuation is provided separately.