The reason life insurance works the way it does comes down to one line in the tax code. Under section 101(a), a death benefit paid because the insured died is not counted as income. No tax on the check. It's the cleanest treatment any asset gets.
Section 101(a)(2) is the exception, and it's called the transfer-for-value rule. Say somebody buys a policy from its owner. The tax-free amount shrinks down to what the buyer paid for it, plus any premiums the buyer paid after that. Everything above that line becomes ordinary income to whoever collects, which means it gets taxed at regular income rates. Take a $1,000,000 policy bought from its owner for $60,000, with $15,000 of premiums paid after the sale. The beneficiary gets $75,000 tax-free and $925,000 taxable.
Gifts generally don't trip the rule. When you give a policy away, the person receiving it takes over your cost basis. Your cost basis is the number you had in it for tax purposes. A transfer that carries your basis along with it is one of the listed exceptions. Which is why handing a policy to your child, or to a trust, usually doesn't create the problem. Selling one does create it.
The other exceptions matter mostly because of who isn't on the list. A transfer to the insured is fine. To a business partner of the insured, fine. To a partnership the insured is a partner in, fine. To a corporation where the insured is a shareholder or an officer, fine. A transfer to a fellow shareholder is not on that list. So two shareholders buy each other's policies to fund a buy-sell agreement, and they have walked right into it. It happens often enough that it's the first thing a good attorney checks when rewriting one.
The 2017 tax law added another layer, called the reportable policy sale rules. Those tightened the gift exception. It no longer covers sales to buyers who have no real family, business, or money connection to the insured. The life settlement market works that way, with investors buying policies from the people who own them. If you're selling a policy to a third party rather than moving it inside a family or a business, assume the rules apply and get the deal reviewed before you sign.
Separate from all of this, there's a three-year rule on the estate side. Give a policy away and die within three years, and section 2035 pulls the death benefit back into your taxable estate as if you'd never transferred it. That's an estate tax problem rather than an income tax problem, and it only bites estates above the exemption amount. But it's the reason attorneys prefer to have a trust apply for and own a policy from day one, instead of moving an existing one in later.
I'm a licensed insurance broker, not a CPA and not an attorney. A change of ownership form takes four minutes to fill out and it can move a seven-figure tax result. Run it past your accountant or your attorney before you sign one. The three roles that form rearranges are in owner, insured, beneficiary: why the three roles matter.