You may not add to your cost basis, the interest expense or the property tax. The property tax may be deducted on Schedule A, if you itemize deductions. Investment interest is also deductible on Schedule A, but is limited to the total amount of your investment income.
If this was a "one off" flip house, it should be reported as a capital loss, as the other reply said. If you are in the house flipping business, then it should be reported as a business loss, on Schedule C, where the interest and property tax would be deductible.
For more info, in making that determination, see a similar question at: https://ttlc.intuit.com/questions/3399983-tax-issues-regarding-flipping-of-a-house
And references at:
https://www.hrblock.com/tax-center/income/real-estate/flipping-houses-taxes/
https://fitsmallbusiness.com/taxes-on-flipping-houses/ https://www.lendinghome.com/blog/how-to-maximize-house-flipping-tax-benefits/
