Interest paid on debts incurred in order to invest (such as ‘margin accounts’) is generally deductible to the extent that it offsets investment income (such as interest, dividends and short term capital gains). Interest payments in excess of investment income can be carried forward in hopes of offsetting future investment income. This calculator can help you better manage the use of debt as an investment tool, and more accurately time your income and interest payments to take best advantage of current deductibility laws and limitations.