The two tests for the same word, and why they point in opposite directions. For gift tax purposes the giver's state of mind does not matter: the IRS applies the tax whether or not the donor intended the transfer to be a gift, which is how a below-market sale to a family member becomes one. For income tax purposes the giver's state of mind is the entire question. The Supreme Court held in Commissioner v. Duberstein, 363 U.S. 278 (1960), that a gift in the statutory sense "proceeds from a detached and disinterested generosity," out of "affection, respect, admiration, charity or like impulses," and that "the most critical consideration" is the transferor's intention. A payment made from "the constraining force of any moral or legal duty," or in anticipation of an economic benefit, is not a gift however the parties label it. The Court was equally clear that the label is not decisive in the other direction: "there must be an objective inquiry as to whether what is called a gift amounts to it in reality," and something that is a gift at common law is "not necessarily a gift within the meaning of the statute."
The employer carve-out, which is the rule that catches people. Section 102(c) states that the exclusion "shall not exclude from gross income any amount transferred by or for an employer to, or for the benefit of, an employee." There is no small-amount tolerance in that sentence. A holiday cash bonus, a gift card, a wedding present in cash from the firm: all of it is wages unless it fits a different statute, and the two the code itself points at are employee achievement awards under section 74(c) and de minimis fringe benefits under section 132(e), neither of which reaches cash or a cash equivalent. The generosity may be entirely genuine. The tax treatment does not turn on that.
What the gift produces is taxed, even though the gift is not. Section 102(b) removes the income from gifted property from the exclusion, and also removes a gift that consists of the income from property rather than the property itself. So a transferred rental house arrives untaxed and its rent is taxable from the first month; a transferred bond arrives untaxed and its interest is reportable. This is the distinction that decides whether a transfer moves a tax bill or merely moves an asset.
Basis follows the giver, and that is the load-bearing difference between giving now and leaving later. Under section 1015 the recipient of a gift generally takes the giver's cost basis and the giver's holding period, so the unrealized gain travels with the asset and is taxed when the recipient sells. Property that passes at death is instead revalued, so the gain accumulated during the owner's life is never subject to income tax. That asymmetry pushes readers toward an obvious strategy, and there is an anti-abuse rule waiting at the end of it: section 1014(e) denies the revaluation where appreciated property was gifted to the person who died within one year of their death and passes back to the donor or the donor's spouse. The gift tax page carries the mechanics of both rules, including the trap on a loss position.
"Gifting moves assets out of your estate" is loose, and the correction is worth knowing. Section 2001(b) computes the estate tax on the taxable estate plus the decedent's post-1976 adjusted taxable gifts, so a taxable lifetime gift is added back at the value it had when it was made. What leaves the transfer tax system is the growth after the gift, not the gift. For a large estate that is a real benefit; it is simply not the benefit the shorthand describes.
The consequences that have nothing to do with tax, and usually matter more. A completed gift is irrevocable, so money given to an adult child is that child's money, reachable by that child's creditors and divisible in that child's divorce. An outright gift to someone who receives income-tested or asset-tested benefits can cost them those benefits, which is the reason such transfers are usually routed through a trust instead. And an agent acting under a power of attorney generally cannot make gifts from the principal's assets unless the document says so expressly, because the Uniform Power of Attorney Act treats the gifting power as one that has to be granted rather than assumed.