@Eaglelord17
The more I think of it- the more it can't be "making it subject to capital gains". Making it a capital gain means treating it as an asset, and the (technically correct) push would be to then treat it like any other investment asset. Interest as a deductible expense, expense and upkeep tracking etc. It becomes an administrative nightmare that forces every home owner to act like a business from a bookkeeping standpoint and realistically wipes out most of any actually tax effect you're trying to implement.
So- not a capital gain. Call a spade a spade and own it: Principle Residence Windfall Tax. Define what a windfall is (any amount above CPI adjusted purchase price, accounting for the reported permit value of upgrades, maybe adding say 0.5% of purchase/improvement price per year of ownership of carrying cost allowance. Make it payable at time of transaction like Ontario's land transfer tax.
Example: Home Selling at 575 today, purchased at 300 in 2018, 100k improvement in 2022.
- Inflation adjusted cost base = 502k (375k (purchase) + 113k (improvement) + 12k (carry cost allowance of house for 8 years) + 2k (Carry cost allowance of improvement for 4 years)))
- Windfall = 73k
- Taxed at 14.5% (lowest federal income bracket = $10,585 tax.