You are saying to add together all the improvements to the purchase price (minus land) as one asset entry with the same date of purchase, and then the date placed in service?
Date of purchase "does not matter" for property improvements done "before" you placed the property in service. Depreciation starts on the date placed in service. Not the date of purchase. So all property improvements done "before" you placed the property in service can be added to the original cost basis and entered as a single asset. Example:
Purchased property in 2010 for $100,000. $80,000 is allocated to the structure and $20,000 to the land.
With just that, (and only that) you would enter:
COST: 100,000
COST OF LAND 20,000
The program (NOT YOU) does the math and assigns $80,000 to the value of the structure.
Now lets say in 2015 you added on a room to your house at a cost of $20,000. On the 2023 tax return you would enter:
COST 120,000
COST OF LAND 20,000
Note that what you paid for the land does not change. Only the value of the structure on that land changes. So the program (not you) would do the math and assign $100,000 to the value of the structure.
If you're renting only 20% of your home, then 20% of $100,000 ($20K) would be assigned to the rental portion and depreciated over 27.5 years. Then 20% of the land value ($8,000) would be assigned to the land, and land is *not* depreciated.
