It depends on what you mean by "investment real estate property". If it is active rental property, then it goes on Schedule E. If it is unproductive or vacant property being held for appreciation, then it goes on Schedule A , line 5b and subject to the 10K total limit.
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The carrying costs (e.g. repairs, insurance & utilities) of investment property are not deductible, staring with tax year 2018. Real estate (property) tax may be deducted on schedule A.
Alternatively, taxpayers can elect to capitalize (add it to your cost basis) the carrying costs of unimproved and nonproductive real property, real property under development or construction and personal property before its installation or use (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 make that election each year. Attach the statement to the return and write “Filed pursuant to section 301.9100-2” on the statement. You may add the carrying costs, incurred in the year of sale, to your cost basis.
Mortgage interest is only deductible to the extent of other investment income and not subject to the 2% of AGI rule, but can be capitalized.
You cannot amend previous year returns to to claim capitalization. (see https://ttlc.intuit.com/community/tax-credits-deductions/discussion/is-it-possible-to-amend-taxes-fo... )
Prior to 2018, carrying costs could alternatively be deducted as investment expenses, a misc. itemized deduction subject to the 2% of AGI threshold. So, filing amended returns for earlier years is an option, for that.
