In 2015, you can gift up to $14,000 without being taxed. REUTERS/Robert Galbraith

You can gift $14,000 a year without declaring it to the IRS.

You can't simply gift your kids an unlimited amount of tax-free money without reporting it to the IRS — a gift tax exists to discourage sheltering income in "gifts."

The IRS determines a maximum amount that you can gift tax-free each year, and a maximum amount you can gift over your lifetime. For 2015, the yearly limit is $14,000 per person — an individual can give that amount to as many people as they want without declaring it to the IRS. That means a couple could pass on up to $28,000 a year to each child; or, if a couple has three grandchildren, the two together can make $28,000 gifts to each of them, for a total of $84,000.

The lifetime limit in 2015 is $5.43 million.

Note that if you gift more than $14,000 in a single year, you won't necessarily be taxed — you just have to account for it, and file the appropriate forms, explains Michael Solari, a certified financial planner at Solari Financial Planning. This means that there will be more paperwork, and potential costs if you're paying for someone to prepare your taxes.

You'll want to keep track of how much you gift above the $14,000 limit though, as that amount will count against your $5.43 million lifetime limit. For example, if you gift your kid $25,000 one year, your lifetime amount will be reduced by $11,000 (the first $14,000 is ignored).

Also keep in mind that if you're gifting your kid on an annual basis, they must cash or deposit the check that same year. So if the tradition is to give a check at Christmas time, make sure they take it to the bank before the new year. "Technically, they have to cash the check the year that they get the check," explains John Gajkowski, a certified financial planner at Money Managers Financial. "And, if the husband and the wife are going to give $28,000 they should cut separate checks."