I paid off my son’s mortgage of $30,000. How do I treat this for tax purposes?

For income tax purposes, you cannot take a deduction for this payment and your son is not taxable on it (it’s a gift to him). For gift tax purposes, the first $14,000 is excluded ($28,000 if your spouse consents to split the gift). The excess is a reduction in your lifetime gift tax exemption amount. The lifetime exemption amount is $5 million indexed annually for inflation, making it $5.25 million in 2013.