On its consolidated Form 1099-B, IB lists four items. Which of these are deductible? "Margin Interest Paid" - this is deductible for sure, per TurboTax on the "Investment Interest Expenses" page Payment in Lieu Paid - no idea what this is, but it's 0 anyway Advisory Fees Paid - same Other Fees Paid - this is over $1k. What are these fees? Market data? TurboTax has a page for "Investment Expenses, other than interest expenses". Can someone confirm whether these "Other fees paid" are deductible and where, ideally by citing a source?