Education

Understanding FIFO Cost Basis for Capital Gains Tax

The First-In-First-Out (FIFO) method is the ATO-preferred approach for calculating CGT. Learn how it works, when to use it, and how it impacts your tax liability on share sales.

1 February 20265 min read

What is FIFO?

FIFO stands for "First-In-First-Out." It's a method for determining which shares you're selling when you own multiple parcels of the same stock purchased at different times and prices.

The Rule: When you sell shares, FIFO assumes you're selling the shares you purchased first.

Why the ATO Prefers FIFO

The Australian Taxation Office (ATO) considers FIFO to be the default method for identifying which shares are sold. While you can use other methods (like specific identification), FIFO is:

  • Simple and consistent
  • Easy to audit
  • Logical chronological ordering

How FIFO Works: An Example

Let's say you bought Commonwealth Bank (CBA) shares as follows:

DateSharesPriceTotal
1 Jan 202450$100$5,000
1 Jun 202450$110$5,500
1 Dec 202450$95$4,750

Now you sell 75 shares at $120 each on 1 Feb 2026.

FIFO Allocation:

  • First 50 shares from Jan 2024 parcel: Cost base $5,000
  • Next 25 shares from Jun 2024 parcel: Cost base $2,750

Capital Gain Calculation:

  • Sale proceeds: 75 × $120 = $9,000
  • Total cost base: $5,000 + $2,750 = $7,750
  • Capital gain: $9,000 - $7,750 = $1,250

Since all shares held > 12 months: 50% discount applies

  • Taxable gain: $625

FIFO and the CGT Discount

One important implication of FIFO: your oldest shares are sold first, which often means:

  1. They've been held longer
  2. They're more likely to qualify for the 50% CGT discount
  3. They may have a lower cost base (if prices have risen)

This can work for or against you depending on price movements.

Alternatives to FIFO

While FIFO is the default, you can use other methods if you maintain proper records:

Specific Identification: Choose exactly which parcel to sell. Requires lot-level tracking and documentation.

Average Cost: Used mainly for managed funds, not generally applicable to direct share holdings.

Best Practices

  1. Document every purchase with date, quantity, price, and fees
  2. Track DRP parcels as separate lots (they each have their own cost base)
  3. Use software to automate FIFO calculations
  4. Keep records for 5 years after selling (ATO requirement)

How Pro Portfolio Tracker Helps

Our platform automatically:

  • Tracks every parcel separately
  • Applies FIFO ordering to sales
  • Calculates the 50% discount where applicable
  • Generates ATO-ready CGT reports

Stop wrestling with spreadsheets and start getting accurate CGT calculations.

Disclaimer: The information provided on Pro Portfolio Tracker is for educational and informational purposes only and does not constitute financial, investment, legal, or tax advice. Any information provided is general in nature and does not take into account your personal objectives, financial situation, or needs. You should consider whether the information is appropriate for you and seek independent professional advice from a registered tax agent or financial adviser before making any investment or tax decisions.

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