While searching for homes and scrolling through listing photos can be fun, saving up for a down payment can be a real challenge. That’s why some home buyers turn to family for a helping hand in the form of the gift of a down payment.

But whenever a large stack of cash changes hands, tax returns can get complicated. Here, realtor.com explains the tax implications involved when it comes to giving of getting a down payment gift.

Who can give you a cash gift for a down payment?

You only can use a cash gift from an immediate relative such as a parent, grandparent, sibling or spouse to help get a mortgage to buy a home. It’s also generally acceptable to receive gifts from a domestic partner or significant other if you’re engaged to be married.

Keep in mind, however, that you’ll have to provide the lender with detailed documentation in the form of a gift letter that states the name of the donor, their relationship to you, the date and amount of the gift.

You’ll also need a statement from the donor saying that the money was given with no expectation of repayment. And watch out for this important condition: The general rule is, if you are putting a down payment of 20 percent or more, it can all be gifted money. But if your down payment is less than 20 percent, some of that needs to come from your own pocket.

How much of a tax-free gift can you give?

One person can give a gift of $15,000 or less to another individual and not have to pay taxes on it. But families can amass a bigger gift under that regulation if each member of a couple trying to get help with a down payment receives $15,000 from each parent.

For example, mom gives $15,000 to her daughter and $15,000 to her son-in-law, and dad does the same. That means that one set of parents could give the couple a total of $60,000 tax-free.

And then the husband’s parents could do the same. All that’s required is that it is a gift, meaning it’s made with disinterested generosity. With the gift tax, any amount received that’s beneath the current $15,000 exclusion amount is not taxable to anyone.

What if the down payment gift is above $15,000?

Down payment amounts above $15,000 and received as a gift must be reported on a gift tax return by the person making the gift—not the beneficiary. But that doesn’t mean the donor will pay taxes. The gifts are added up over time and offset against the lifetime exclusion on gifts, which is currently $11.4 million.

The purpose of filing the return is to track your lifetime gift amount, which will be used in calculating tax on your estate when you pass away. If you give more than $11.4 million while still alive, the gift tax rate kicks in, which can be range from 18 percent to 40 percent.

What if you don’t report the down payment gift?

There is generally a three-year statute of limitations on filing a gift tax return, although that doesn’t begin until a return is filed. If you don’t file the gift tax return within that period, the IRS can assess a gift tax, in addition to penalties and interest, on a reportable gift that was not adequately disclosed on a return, years—even decades—after the gift was made.