I purchased a property that went under contract on the 1st of July 2020 and the title was transferred on the 1st of August 2020. The purchase price was $420,000 and I paid $3000 in stamp duty and $1,100 in legal fees at the time of purchase. I lived in the house from the time of purchase and decided to rent the lower level (which represents 50% of the SQ Meters) to a tenant from the 1st of July 2022. I receive $280 per week in rental income. The tenant lived downstairs until the house sold and went under contract for $680,000 on the 30th of June 2023.
I am aware of the partial CGT discount that is calculated by taking the capital gain and multiplying it by the non-main residence days divided by the total ownership days BUT I am a bit confused because I only rented out 50% of the home and it remained my main residence for the entire period of ownership.
I know that If the main residence was used to produce assessable income (rent) > 20/08/1996 the cost base will be changed to the market value on the date on which it started to produce assessable income (was rented out) but how do I do a retrospective valuation of the property?
Looking for some advice so I can accurately calculate the capital gain.