Net unrealized appreciation: the employer-stock tax break that hides in your 401(k)

By Tom, CPA · Updated October 25, 2026

TL;DR: If your 401(k) holds appreciated stock of your employer, a lump-sum distribution of that stock to a taxable account can let you pay ordinary income tax only on the plan's cost basis now, with the appreciation (NUA) taxed later at long-term capital gains rates when you sell. It requires a qualifying triggering event and a full distribution within one tax year.

Educational only, not tax, legal, or investment advice. Examples are illustrations, not predictions. Rules and limits change; verify current figures and talk to a qualified professional about your situation.

Some people spend their careers buying their employer's stock inside the 401(k). Sometimes the stock soars. That's great, until you realize that withdrawing it from the plan the normal way means paying ordinary income tax on every dollar, including the dollars of growth that would have been long-term capital gains in a regular brokerage account.

Net unrealized appreciation, or NUA, is the tax code's consolation prize. It's a niche strategy with sharp edges, but for the right person it can convert a big chunk of ordinary income into capital gains. Think of it as the tax code saying, "Fine, you were loyal. Here's a gift card."

CPA Warning Label: NUA is a one-shot deal with strict sequencing. Roll the company stock into an IRA first and the opportunity is generally gone for good.

What NUA is

IRS Publication 575 defines NUA as "the net increase in the securities' value while they were in the trust." If you receive a distribution of employer securities from a qualified plan, you may be able to defer tax on that NUA. If the distribution is a lump-sum distribution, tax is deferred on all of the NUA unless you choose to include it in income.

The pieces:

• Cost basis: what the plan paid for the shares. Taxed as ordinary income in the year of distribution (and possibly subject to the 10% additional tax if under 59½ and no exception applies).
• NUA: the growth while inside the plan. Not taxed at distribution; taxed as long-term capital gain when you sell, regardless of how long you hold after distribution.
• Post-distribution growth: taxed as short- or long-term gain depending on how long you hold after distribution.

The lump-sum distribution requirement

Per Publication 575, a lump-sum distribution for this purpose is the distribution of a participant's entire balance, within a single tax year, from all of the employer's qualified plans of one kind (pension, profit-sharing or stock bonus), paid because of:

• The participant's death,
• Reaching age 59½,
• Separation from service (for employees), or
• Total and permanent disability (for self-employed individuals).

The whole balance must leave the plan in one calendar year after the triggering event. The non-stock portion can usually be rolled to an IRA as part of the same lump sum, and the company stock goes in kind to a taxable brokerage account. Partial distributions in an earlier year after the triggering event can spoil it, so sequencing matters.

Illustration: the numbers

Illustration (assumptions): Fran, 58, separated from her employer this year. Her 401(k) holds $700,000: $500,000 in employer stock with a plan cost basis of $100,000, and $200,000 in mutual funds. She does a lump-sum distribution in one tax year.

• $200,000 of funds: direct rollover to an IRA. Not taxed now.
• Employer stock: distributed in kind to a taxable brokerage account.
• Ordinary income this year: the $100,000 cost basis. Because she separated in or after the year she turned 55, the Rule of 55 exception covers the 10% additional tax.
• NUA: $400,000, not taxed until sold, then at long-term capital gains rates.

Compare: if she rolled all the stock to an IRA, every dollar eventually withdrawn would be ordinary income: $500,000 (plus growth) instead of $100,000 ordinary plus $400,000 capital gain. At a 24% ordinary rate versus 15% capital gains, the rough difference on the $400,000 is $36,000 (9% of $400,000), ignoring state tax and timing. The NUA route costs tax now on the $100,000 basis, which is the price of admission.

When NUA tends to make sense

• Low cost basis relative to value. The lower the basis, the better. If the basis is 80% of value, you pay ordinary income on most of it now for little benefit.
• A gap between your ordinary and capital gains rates. Bigger gaps mean bigger savings.
• Willingness to pay some tax now. The basis is taxed in the distribution year, so a lower-income year (like the first year of retirement) can help.
• A plan to diversify. Holding a large single-stock position is risky. NUA doesn't require keeping the stock; selling immediately after distribution still gets long-term rates on the NUA.

When NUA tends not to make sense

• High basis, small appreciation.
• You'd prefer Roth conversions of that money in low-bracket years and expect your ordinary rate in retirement to be low.
• You'll leave the stock to heirs. NUA doesn't get a step-up in basis at death, unlike most taxable holdings; heirs still owe tax on the NUA.
• The distribution year would push you into much higher brackets or affect ACA credits or IRMAA.

Common mistakes

• Rolling the stock to an IRA first. Once employer stock is in an IRA, NUA treatment is generally no longer available.
• Taking a partial distribution after the triggering event in an earlier year, which can disqualify a later lump sum for that triggering event.
• Missing a plan. All plans of the same kind from that employer must be emptied in the same year.
• Not confirming basis. Plans track per-share cost basis; request a statement before deciding.

Reporting

The plan's Form 1099-R reports the distribution, including the NUA amount in a separate box. Your broker needs the plan's cost basis for the shares, so when you later sell, the gain is computed from the basis you already paid tax on. Keep the 1099-R and the plan's basis statement with your permanent records, because the broker's records may not reflect the NUA rules correctly.

A decision checklist before the distribution

1. Confirm the triggering event and the tax year you'll use for the lump sum.
2. Get a per-share cost basis statement for the employer stock from the plan administrator.
3. List every plan of the same kind sponsored by that employer, since all must be emptied in the same year.
4. Check whether any distribution has already been taken after the triggering event.
5. Decide which shares go in kind to a taxable account. You don't have to use NUA on all of them; some lots with high basis can be rolled to the IRA instead.
6. Estimate the tax on the basis portion, including state tax, ACA credit effects, and IRMAA if you're near Medicare age.
7. Plan how and when you'll diversify the concentrated position.

Lot selection is the hidden lever. Plans often track shares bought at different prices, and some administrators will let you send only the low-basis lots to the brokerage account while the rest rolls to an IRA. That can capture most of the benefit with a smaller basis tax bill. Ask; the worst answer is "no."

How NUA fits early retirement

For someone retiring at 55 or later with lots of employer stock, NUA can reduce lifetime taxes and create a taxable account that funds the bridge years, with sales taxed at capital gains rates (which can be 0% within the bracket for low-income years under current law). It pairs with the Rule of 55 for the basis portion. Before acting, compare with a Roth conversion approach and look at rollover sequencing, because the choice is generally irreversible.