For income tax purposes, there’s no tax on gifts—to make or receive them. For federal gift tax purposes, there’s an annual exclusion ($14,000 in 2015 and 2016). Above that, you can apply your lifetime exclusion ($5.43 million in 2015 and $5.45 million in 2016). If you’re married and your spouse consents to the gift, you can double these amounts.
Interest on debt used to carry investments, but not including interest expense from a passive activity. Deductions are limited to net investment income.