Net Unrealized Appreciation: The 401(k) Company Stock Tax Break

Net unrealized appreciation, or NUA, is the growth in your employer's stock while it sat inside your 401(k). The NUA tax rule lets you move that stock out of the plan in kind, pay ordinary income tax only on what the shares originally cost, and have the appreciation taxed later at long-term capital-gains rates instead of ordinary income rates. For someone with a large block of highly appreciated company stock, that difference in rates can be substantial.

The rule exists because employer stock held in a retirement plan is taxed unusually generously if you handle it correctly, and unusually harshly if you do not. Roll the stock into an IRA like everything else and you give up the break entirely; every future dollar becomes ordinary income. Use the NUA election properly and you split the tax into a small ordinary-income piece now and a capital-gains piece later. This article explains the mechanics, the strict conditions, and the traps that quietly disqualify people.

The numbers below are illustrative examples to show the arithmetic. They are not advice for your situation, and tax rules change. Confirm your own figures and eligibility with a tax adviser before acting, because an NUA election is generally irreversible once made.

What NUA is and why it matters

Inside a 401(k), nothing is taxed as it grows. The tax bill comes when money leaves the plan, and normally it leaves as ordinary income, taxed at your regular rate. That is fine for cash and funds. It is a poor deal for company stock that has grown a lot, because all of that growth would be taxed at ordinary rates, which are typically higher than long-term capital-gains rates.

NUA is defined simply:

NUA = market value of the shares when distributed − their cost basis in the plan

The cost basis is roughly what the plan paid for the shares (or the value when they were contributed). The NUA is everything above that. The special tax treatment, set out in Section 402(e)(4) of the Internal Revenue Code, lets you separate the two:

• The cost basis is taxed as ordinary income in the year you take the distribution.
• The NUA is not taxed at distribution. It is taxed only when you eventually sell the shares, and then at long-term capital-gains rates, regardless of how long you actually hold them after the distribution.

Here is an illustrative example. Suppose your 401(k) holds employer stock worth $200,000, with a cost basis of $40,000. The NUA is $160,000.

• At distribution, you pay ordinary income tax on the $40,000 basis.
• The $160,000 of NUA is taxed only when you sell, at long-term capital-gains rates.

Compare that with rolling the whole position into an IRA. There, the full $200,000 becomes ordinary income whenever you withdraw it, and the favourable capital-gains treatment is gone for good. That contrast is the whole reason to learn the rule before you do a routine rollover, the kind covered in our 401(k) rollover guide.

The strict conditions for NUA treatment

The catch is that NUA only works inside a tightly defined transaction. Two requirements do most of the work.

A triggering event. You can only use NUA in connection with one of these: separation from service (leaving the employer), reaching age 59½, death, or total disability. Without a qualifying trigger, the door is closed.

A lump-sum distribution. You must empty the entire account, all of it, within a single tax year, following the triggering event. That means distributing the whole balance of the plan (and others of the same type) in one year, not just the stock. The stock goes in kind to a taxable brokerage account; the rest can be rolled to an IRA in the same year without spoiling the election.

A few details sharpen those rules:

• The shares must be distributed in kind, as actual stock, not sold inside the plan first. Once the plan sells the stock, there is nothing appreciated to move out, and the chance is lost.
• The stock must come from a tax-deferred plan such as a 401(k) or ESOP. Stock in a Roth 401(k) does not use NUA, because Roth distributions are already tax-free.
• It must be genuine employer securities of the company you worked for.

The traps that quietly disqualify you

This is where careful people lose the benefit, often without realising it until the tax return is prepared.

Taking any other distribution in the wrong year. The lump-sum requirement means the qualifying distribution must empty the account in one tax year. If you took a partial distribution after your most recent triggering event but before the lump-sum year, you can break the lump-sum status. A stray withdrawal can undo the whole election.

A plan loan that is offset. If you have an outstanding 401(k) loan that gets treated as a distribution along the way, it can interfere with the single-year, full-balance requirement. Loans need to be cleared up thoughtfully before an NUA distribution.

Rolling the stock into an IRA by default. The most common and most costly mistake is the simplest: letting the stock roll into an IRA with everything else because that is the standard move. Once the appreciated shares are in an IRA, the NUA opportunity is permanently gone, and all future growth and basis alike become ordinary income on withdrawal.

Forgetting the early-distribution penalty on the basis. The cost-basis amount taxed as ordinary income can also be exposed to the additional 10% early-distribution penalty if you are under 59½ and no exception applies. The NUA portion is not subject to that penalty, but the basis can be.

Because these are easy to trip and hard to reverse, NUA is one of the areas where it pays to map the sequence of moves before doing any of them. It interacts directly with the broader sequencing decisions in retirement tax strategies.

When NUA is worth it, and when it is not

NUA is not automatically the right call. It shines in some situations and underwhelms in others.

It tends to help most when:

• the stock has appreciated a great deal, so the NUA is large relative to the basis, and
• your ordinary income tax rate is meaningfully higher than the long-term capital-gains rate that will apply to the NUA.

It tends to help less when:

• the cost basis is high relative to the current value, because you pay ordinary income tax on that basis now for a smaller capital-gains benefit, or
• you would otherwise keep the stock sheltered in an IRA for many years, where continued deferral might outweigh the rate advantage.

Approach	Tax on basis	Tax on growth
NUA election (stock to brokerage)	Ordinary income now	Capital gains when sold
Roll everything to an IRA	None now	Ordinary income on withdrawal

There is also a concentration-risk angle. Holding a large position in a single employer's stock is risky regardless of the tax treatment, and the NUA shares sit in a taxable account where selling triggers tax. Some people diversify gradually after the distribution, accepting capital-gains tax as they sell down. Balancing the tax break against the risk of an undiversified position is part of the wider question of how to turn savings into a stable retirement, discussed in creating retirement income from savings.

One more interaction worth flagging: a partial NUA election is sometimes possible, taking the most-appreciated lots as NUA and rolling the rest to an IRA. This adds flexibility but also complexity, and it has to fit within the same single-year lump-sum rules.

How NUA fits the bigger picture

NUA is a narrow, technical rule, but it sits inside the broader project of deciding which dollars to tax when. The same instinct that drives a Roth conversion, choosing to control the timing and character of tax rather than letting it default, is what makes NUA worth understanding. The shares that come out as NUA also stop being part of your tax-deferred balance, which can affect future required distributions and the planning around them.

If you hold appreciated employer stock in a workplace plan, the single most useful thing you can do is pause before any rollover and check whether NUA applies. The standard, sensible advice for almost every other account, roll it into an IRA, is exactly the advice that destroys this particular break. For the general account-type landscape that surrounds this decision, see tax-advantaged retirement accounts.

Frequently asked questions

Do I have to sell the stock right after the NUA distribution?

No. You can hold the shares as long as you like in your taxable brokerage account. The NUA portion keeps its long-term capital-gains character whenever you eventually sell, even if you sell the next day. Any additional gain after the distribution date is taxed under the normal rules, based on how long you hold from that point.

What happens if I accidentally roll the stock into an IRA?

The NUA opportunity is generally lost. Once the appreciated employer shares are inside an IRA, the special treatment no longer applies, and future distributions are taxed as ordinary income like any other IRA money. This is why the stock must be distributed in kind to a taxable account rather than rolled over. Reversing it is usually not possible, so the sequence matters.

Is the cost basis amount subject to the early-withdrawal penalty?

It can be. The cost basis taxed as ordinary income at distribution may also face the additional 10% early-distribution penalty if you are under 59½ and no exception applies. The NUA portion itself is not subject to that penalty. Because the penalty rules have exceptions and change, confirm your own position before assuming.

Does NUA work with a Roth 401(k)?

No. Roth 401(k) distributions are already tax-free when the requirements are met, so there is no ordinary-income-versus-capital-gains problem to solve. NUA applies to employer stock held in a tax-deferred plan such as a traditional 401(k), ESOP, or other qualified plan, where the growth would otherwise be taxed as ordinary income.

This article is educational and not personal financial or tax advice. NUA elections are technical and generally irreversible, and the tax rates and rules change over time. Confirm your cost basis, eligibility, and the full sequence of distributions with a qualified tax adviser before acting.