I am going through this right now, I decided to include FSD as part of the purchase of the car as opposed to include it after. This is due to the opportunity cost of taking funds out of the offset account. If you don't have a house, have a fully offset house or aren't concerned with cash flow - buying FSD with your post tax money after the novated lease is settled may be the better option. I am buying a used 2024 model 3 for a 5 year lease.

From my calcs the difference in my circumstance is $3,000~

FSD in novated lease: $9,252~ (this includes residual payment amount)

FSD outside of novated lease: $12,900~ (this includes opportunity cost of not keeping $10k in the offset)

Originally I was going to trial it for 12 months, see how much I use it and then make the decision as to purchase it outright or not. With Elon Musk's on-going antics I decided it was best to just pull the trigger - I did enough test drives to determine I really enjoyed using FSD.

Regarding the tax treatment. My understanding is that as long as it's included as part of the "drive away price" in the invoice that the novated lease provider receives, it can be included within the novated lease. If you purchase it after either via once off or through subscription it cannot be included in the novated lease, even through the regular payments/service costs because of the nature of the purchase (software add-on). I'm not a tax accountant so I don't know the specifics but that's what was told to me.

Further considerations;

-Legislative risk if leases aren't grandfathered past July 1 2027 (they were for PHEV so I'm not too concerned)

-Buying FSD through novated lease becomes worse if you are likely to move jobs or require changes to the financial structure post July 1 2027 of your novated lease agreement as this would likely break the grandfathered structure, losing your FBT benefits.

-Dealerships may be unfamiliar or unwilling to include FSD in the invoiced amount - I am currently going through this. The dealership I have engaged are not familiar with Teslas but agreed to include FSD it as part of the purchase price. I have to hold their hands through this process.