CGT Cost Base Checklist: Records You Need to Reduce Capital Gains Tax

General information only. This is not tax or financial advice. Consult a registered tax agent for advice specific to your situation.

Accurate CGT calculations depend on knowing your cost base. The cost base isn’t just what you paid for an asset — it includes a range of costs that reduce your taxable gain. But to claim these costs, you need the records to prove them.

This guide provides a practical checklist for tracking your CGT records.

What is the cost base?

The cost base is the total of five elements:

Acquisition cost — the purchase price
Incidental costs — costs of buying and selling
Ownership costs — certain costs of holding the asset (limited)
Capital expenditure — improvements to the asset
Costs to establish, preserve or defend title

A higher cost base means a lower capital gain and less tax.

The cost base checklist

Shares and ETFs

Acquisition records:

Contract notes showing purchase price, date, and brokerage
DRP (dividend reinvestment plan) statements showing reinvested amounts and dates
Corporate action notices (share splits, mergers, demergers)
Bonus share allocations

Incidental costs to include:

Brokerage on purchase (added to cost base per ITAA 1997, s 110-25)
Brokerage on sale (reduces capital proceeds per ITAA 1997, s 116-20 — same net effect)
Financial adviser fees directly related to the acquisition

Records to keep:

All contract notes from your broker
Annual holding statements
Corporate action correspondence
Tax component statements for ETFs (showing CGT cost base adjustments)

Important: Many ETFs adjust their cost base annually through tax statements. If you don’t track these adjustments, you may overcalculate your gain.

Investment property

Acquisition records:

Contract of sale showing purchase price
Settlement statement showing stamp duty and legal fees
Loan documents (for any capitalised costs)

Incidental costs to include:

Stamp duty
Legal and conveyancing fees
Valuation fees for purchase
Building and pest inspections
Buyer’s agent fees

Ownership costs (limited):

Interest on loans is generally NOT included (you claim it as a rental deduction instead)
Council rates and insurance are NOT included

Capital expenditure to include:

Renovations and improvements that add value or extend useful life
Extensions and additions
Landscaping that adds value
Not repairs or maintenance (these are rental deductions)

Sale costs (reduce capital proceeds, not cost base):

These costs reduce your capital proceeds under ITAA 1997, s 116-20, which has the same effect as increasing your cost base — they reduce your capital gain:

Agent’s commission
Legal fees for sale
Marketing and advertising costs
Styling and staging costs (if required for sale)

Records to keep:

Original purchase contract and settlement statement
All renovation receipts and invoices
Building permits and approvals
Depreciation schedules
Sale contract and settlement statement
Agent commission invoices

For a complete walkthrough of calculating CGT on rental property, see selling a rental property: CGT guide.

Managed funds and unit trusts

Records needed:

Application form showing initial investment
Regular statement showing all transactions
Annual tax statements showing:
- Cost base adjustments
- Non-assessable amounts (which reduce cost base)
- Tax-deferred amounts
- CGT concession amounts

Important: Tax-deferred distributions reduce your cost base. If you don’t track these, you’ll understate your capital gain when you sell.

Cryptocurrency

Records needed:

Exchange records showing all purchases (date, amount, price, fees)
Exchange records showing all sales
Wallet addresses and transaction hashes
Records of any swaps or conversions (each is a CGT event)
Airdrops and their market value when received

Challenges:

Many exchanges don’t provide comprehensive tax reports
Swapping between cryptocurrencies triggers CGT events
Lost or forgotten records are common

Tools: Consider using cryptocurrency tax software that connects to exchanges and wallets to track your cost base automatically.

How long to keep records

The ATO requires you to keep records for:

5 years from the date you lodge the tax return that includes the capital gain or loss
The entire ownership period plus 5 years after sale if you’re claiming carried-forward losses

For assets held for many years, this means keeping records for potentially decades.

Practical tips:

Scan paper documents and store digitally
Use cloud storage with backup
Organise by asset and year
Download and save contract notes from broker platforms (they may not keep them forever)

Common cost base mistakes

1. Forgetting brokerage

Brokerage on purchase increases your cost base, while brokerage on sale reduces your capital proceeds. Both reduce your capital gain — don’t forget either. On frequent trades, this adds up.

2. Missing DRP parcels

Each dividend reinvestment creates a new parcel with its own cost base and acquisition date. Forgetting these leads to overstated gains.

3. Ignoring ETF cost base adjustments

ETF tax statements often show cost base adjustments that reduce your cost base over time. If you don’t track these, you’ll underpay CGT initially but overpay when you eventually sell.

4. Including repairs as capital costs

Repairs and maintenance on investment property are revenue deductions, not cost base additions. Only improvements that add value or extend useful life are capital.

5. Losing records

Broker platforms may not keep records forever. Download and save your own copies.

Special situations

Inherited assets

When you inherit an asset, your cost base depends on when the deceased acquired it:

Pre-20 September 1985: Your cost base is the market value on the date of death
Post-20 September 1985: Your cost base is the deceased’s cost base

You’ll need records of the original acquisition or the valuation at date of death. See our full guide on CGT on inherited property for more detail.

Gifted assets

If you receive an asset as a gift, your cost base is generally the giver’s cost base. You’ll need records from them.

Relationship breakdown

Assets transferred between spouses as part of a relationship breakdown typically roll over at the transferor’s cost base. Keep the original records.

Digital tools

Several tools can help track cost base:

Broker platforms — most provide downloadable transaction history
Portfolio trackers — apps like Sharesight track cost base and CGT automatically
Spreadsheets — simple but requires discipline
Crypto tax software — essential for cryptocurrency tracking

The key is consistency — choose a system and use it for all transactions.

Key takeaways

Cost base includes more than just the purchase price
Every component needs documentary evidence
Keep records for the entire ownership period plus 5 years after sale
Digital storage with backup is essential
Don’t forget adjustments from ETF tax statements and DRP
Repairs are not capital costs — only improvements

Capital Gains Tax Calculator — enter your cost base to calculate CGT