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How I Discovered I'd Been Overpaying CGT For 8 Years
(And Why Most Aussies Are Too)

By David | Wed, August 27, 2025 | 08:12 am
"Okay David, your CGT for this year is $13,124."

I winced. Knew it would be bad — I'd taken some profits to rebalance. But thirteen grand?

"That seems... high," I said.

Sarah shrugged. "You sold quite a few old shares. We use the standard FIFO method which means we match the sale to your oldest shares first. Those CBA shares you bought in 2018? Big gains there."

"What if we didn't use FIFO?" I asked.

"Well, there's LIFO — last in, first out. Or specific parcel selection. But honestly David, FIFO is the standard. It’s what everyone uses."

It’s what everyone uses…

The Zoom came to an end, but that phrase stuck in my head.

I couldn't help but wonder…

Why is it what everyone use ? What would happen if we didn’t use FIFO? What if we use specific parcel selection?

After all, no one builds exceptional wealth doing what everyone does.
My Heart Sank When I Did The Math
Next morning, I pulled up my trade history. 10+ years worth.

I started with just one stock — CBA. I'd been buying it regularly for years. Some purchases at $53, others at $85, some at $95 and $105. Last year, I sold $50,000 worth to diversify into international ETFs, and the shares were sold at a price of $123.

My accountant, using the standard FIFO (First-In, First-Out) method, sold my oldest shares first. Those were the ones I bought for $53. The result was a massive capital gain, landing me with a painful CGT bill of $6,687.

Then I went to ChatGPT…
I ran the numbers again.

If I’d chosen to sell my most recent, more expensive shares — the ones I bought for $105 — the gain would have been much smaller. My CGT bill would have been only $1,720.

The difference? $4,967 on ONE trade.

If I’d applied this across my 10+ years of investing and all my other trades, how much more money would I have been able to keep from the ATO and invest back into the market?

I booked a call with Sarah immediately.
What My Accountant Had To Say About My Math
"Sarah, about CGT calculation methods..."

"Oh David, you're not going down some internet rabbit hole are you?"

"Just hear me out. What if instead of FIFO, we used specific parcel selection to minimize my tax bill?"

Long pause.

"Look David, I'd love to help, but do you know how much time that would take? I'd have to analyze every single holding, every purchase, model out different scenarios... I'd have to charge you thousands just for the analysis. I’m not sure it would be worth it for you."

I didn’t push it further.

This was the moment I realised most accountants just don't have the time or tools to optimize your CGT strategy.

They use FIFO because it's the standard. Calculating different tax scenarios of selling different parcels of shares across every one of their clients just isn’t worth it.
The Spreadsheet Nightmare That Nearly Broke Me
I decided to try it myself.

How hard could it be?

I opened up an excel spreadsheet.

I spent hours downloading and uploading CSVs of my transaction history and trying to organize the numbers. 

But the more I worked on it, the harder it got.

Try modeling out CGT scenarios across 20 different stocks, each with 5-10 different purchase parcels, considering the impact on your marginal tax rate, long-term vs short-term tax all while tracking AMIT cost base adjustments and DRPs...

…in a spreadsheet.

My head was pounding. My formulas kept breaking. And I couldn't tell if I was minimizing my tax bill or accidentally maximizing it.

Worse, I was terrified of making an error. One wrong calculation could mean an ATO audit, penalties, interest charges.

I could see why Sarah was OK sticking with FIFO.

The stress wasn't worth it.

But there had to be another way.
Reaching Back Out To My Financial Confidante
So I revisited my last convo with ChatGPT:
My natural follow up question was…
The summary:
After reading through each of their Trustpilot reviews, Navexa seemed the best option.

But I started a free trial with both anyway.
The Test That Revealed How Much I'd Been Overpaying
Annoyingly, to optimize and report my taxes properly, I needed another subscription.

Navexa felt more modern, had a built-in AI and came with a six-month money-back guarantee. So I went with them.

Signed up that night. Uploaded my transaction history from different brokers and set up the integration to automatically forward all future trades.

Once I’d finished setting up my account I clicked into ‘Tax Overview.’
The total capital gain for the year aligned with my accountant.

But here's where it got interesting.

I clicked ‘Modify’ on Tax Settings and was given these options on CGT calculation:
Just like my accountant, the default was FIFO.

But unlike my accountant, this had four other options (not including their built-in parcel selection tool.)

I went with "Minimize CGT" as I assumed analysed that my entire portfolio for the full financial year and matched specific parcels to create the lower possible CGT.

I clicked it.



Within seconds, it re-calculated the CGT across my entire portfolio.
The difference was staggering:

FIFO: $13,124.49

Minimize Gain: $4375.75

This year’s saving: $8,748.74

Same investment account. Different CGT calculation.

I couldn’t believe it.

Back to GPT:
The Moment I Realized I'd Been An Amateur
This wasn't just portfolio tracking. This was professional-grade tax optimization. 

Every serious business optimizes their tax strategy. Every wealthy investor.

But retail investors like you and me? 

We get stuck with FIFO because "that's how it's always done."

The sad truth is unless you pay for the top accountants who focus on saving you money, most accountants' only priority is making sure you’re ATO compliant. 

I'd been treating my portfolio like a hobby when it should be run like a business.

A business that was on track to make me financially independent.

To summarise the effect of Navexa on my investing:
Week 1: I Made an ROI of 2916.25% the Annual Subscription
Navexa’s annual subscription cost me $300.

I saved $8748.74 by switching to minimise CGT. 

ROI in one week: 2916.25%.
Week 2: My Accountant Actually Thanked Me
I sent Navexa ATO myTax report to Sarah wondering what she’d say.

She loved it.

She was both surprised and skeptical at how I’d managed to do it.

I explained Navexa was used by accountants like the guys at Scope Accounting to help them with their client work and she said she’d give it a go.
Month 6: The Compound Effect Kicks In
Here's what nobody tells you about CGT optimization:

It compounds.

Choosing to ‘Minimise CGT’ isn’t some magic trick that means you avoid the ATO forever.

If you decide to sell ALL your shares in a stock in five years time, you’ll end up paying the full CGT you would have with FIFO this year.

But the difference is the compounding effect.

Money today is worth more than money tomorrow.

Every dollar you don't pay in unnecessary tax can be invested into your portfolio.

Over 10 years? That $8,749 can become $22,700+ (assuming 10% returns). 

Over 20 years? $58,900+

This isn't just about this year's tax bill. 

It's about accelerating your portfolio growth over the long term. 
The Features Nobody Talks About (But Should)
People think portfolio tracking is about seeing fancy charts of your investments.

Yes, that's great. It's been over a year since using Navexa and I love knowing my exact performance and allocations across all my holdings.

But it's the boring stuff that makes Navexa invaluable:

Automatic AMIT cost base adjustments (VGS, VAS, A200 — all handled automatically) 

DRP tracking (no more manual entry of reinvested dividends) 

Multi-broker sync (CommSec, Selfwealth, Interactive Brokers — all in one place)

Year-round tax visibility (know your CGT liability before you trade)

Real-time tax modeling: Ask the AI "what happens if I sell 500 shares of VAS" and get instant CGT calculations

ATO-compliant reporting: Everything documented and formatted for your accountant

Data ownership: Export everything anytime—- your records, your control
18 Months Later: I love tax time.
I never thought I'd say this.

But I almost enjoy tax time now.

There's a guilty satisfaction knowing I'm optimizing tax like the top 1% of investors, and it takes me no time or energy.

I sleep better knowing I'm not overpaying tax.

Every rebalancing trade gets optimized automatically.

My accountant loves working with me (clean data = faster work = lower fees).

I saved thousands in CGT again this tax year. My total savings over two years is now more than my entire emergency fund used to be.

But the best part?

Finally, I have complete control over my portfolio.

I know my exact asset allocations across every account. I know my CGT obligations year-round. I know the tax implication of every potential trade. I know my sector weightings and geographic exposure. I track dividends vs capital growth contributions to my returns.

And I almost NEVER have to manually input a trade. All tracking and calculations happen automatically.

It sounds cringe, but I feel like the CEO of my financial future.

I'm making informed decisions based on data, not gut feeling.
Don't Wait Like I Did — Use It This Tax Season
If you're serious about financial independence, you need serious tools.

You wouldn't run a business on a calculator. Don't build generational wealth with amateur tools.

This isn't just another subscription — it's wealth-building infrastructure. 

Here's what makes this a no-brainer:

14-day free trial: Test everything risk-free 

6-month money-back guarantee: If it doesn't save you more than the subscription cost, get a full refund 

Your data stays yours: Export everything anytime, no vendor lock-in 

Bank-grade security: Your financial information stays private and encrypted

Calculate your potential CGT savings today.

Upload your trades, run the "Minimize CGT" calculation, see the difference.

If it doesn't save you money on your very first optimization, cancel immediately.

But if you're like me — and thousands of other FI investors — you'll wonder how you ever managed without it.
Don't overpay the ATO like I did for 8 years. Your future financially independent self will thank you.

David, Melbourne

P.S. Last month I helped my brother set up Navexa. He doesn't want me to share his numbers, but let me just say he bought me dinner the following week. Very good dinner.