One of the most common examples of investment interest expense involves the use of a margin loan at a brokerage. (turbotax.intuit.com)
For example, if you have $ 3,000 in margin interest but net investment income of only $ 1,000, you can only deduct the $ 1,000 in investment interest in the current year. (turbotax.intuit.com)
Tax deduction of investment interest is a moot point anyway since you note that you don't earn enough to pay taxes. (canadiancapitalist.com)