Copy and pasted from IRS (hence the conflicting information):

13. What investment expenses are deductible in computing NII?

In order to arrive at Net Investment Income, Gross Investment Income (items described in items 7-11 above) is reduced by deductions that are properly allocable to items of Gross Investment Income. Examples of deductions, a portion of which may be properly allocable to Gross Investment Income, include investment interest expense, investment advisory and brokerage fees, expenses related to rental and royalty income, tax preparation fees, fiduciary expenses (in the case of an estate or trust) and state and local income taxes.