I spent 10k to demolish a carport and fill in a swimming pool at my rental property.?

Nope, you add it to your land basis.

IRS publication 551

Demolition of building.

Add demolition costs and other losses incurred for the demolition of any building to the basis of the land on which the demolished building was located. Do not claim the costs as a current deduction.

Hi so if it's a rental property you don't own it. so you can claim nothing.

As landlord and real estate investor, there are many things I write off as an expense of doing business as a real estate investor and landlord.

You might be able to write this expense off as a deduction, however it would not be under the heading of repair. You demolished two items.

The cost basis has nothing to do with the expenses of operating a rental. You are able to deduct depreciation on your rental property. At that time your cost basis would be a consideration in you taxes, unless you have depreciated the rental down to zero. At that point it would not matter. When you no longer have depreciation in your property to deduct, normally it is time to consider selling and buying another rental or do a 1030 exchange.

You should present this situation to the person that does your taxes and see how you are able to use this expense as a tax deduction.

I hope this has been of some benefit to you, good luck.

"FIGHT ON"

No. It has to be added to the basis of the property.

In the UK this is capital expenditure which can be set against a sale, but not rental income.

You should find a very good tax guy. Not ask us on here- to many variables.---but I bet you can find a way with right documents.