Q. Can I deduct my 10 years property tax when selling my investment property?
A. No.
You coulda shoulda deducted them, in the year you paid them (as an itemized deduction).
Alternatively, taxpayers could have elected to capitalize (add it to your cost basis) the carrying costs of unimproved and nonproductive real property (Regs. Sec. 1.266-1(b)(1)). The election is made with the tax return by its due date, including extension, by attaching a statement. You cannot wait until you sell the property, but must have made that election each year.