Investment interest expenses are deductible as an itemized deduction on Schedule A of the tax return. If your portfolio includes both taxable and tax-exempt securities, only the taxable expenses can be deducted. If your standard deduction is higher than your itemized deductions, you won’t be able to deduct the investment interest expenses you paid.
Don’t confuse investment interest expense with qualified mortgage interest that you paid on your home. That interest is reported on a separate line on Schedule A.