Tax Bomb: Employer Stock Inside $4.2M 401(k) Could Cost Dearly

A senior director at a public mega-cap company is wrapping up her career at age 61. Her 401(k) sits at $4.2 million, the product of nearly three decades of contributions, an employer match paid in company stock, and steady ESPP participation. Of that balance, $880,000 is concentrated in her employer’s shares, with a cost basis of just $185,000 and embedded appreciation of $695,000.

Her default instinct is to roll the entire balance into an IRA. That single decision would permanently convert $695,000 of long-term capital gains into ordinary income, payable at her marginal rate as she draws the money down. But the IRS allows a different path that most retirees never hear about it.

This scenario surfaces repeatedly in retirement forums, where listeners with concentrated employer stock are routinely told to roll it all to an IRA. That advice is fine for the bond fund and the target-date equity sleeve. It is wrong for employer stock, experts say.

A Case Study

• Age and status: 61, separating from service this year
• Total 401(k): $4.2 million
• Employer stock inside the plan: $880,000 market value, $185,000 basis
• Net Unrealized Appreciation: $695,000 eligible for long-term capital gains treatment
• What’s at stake: roughly $75,000 to $110,000 in lifetime federal tax

Inside a 401(k), every dollar comes out as ordinary income. At her likely retirement marginal bracket, that means federal rates of 24% or 32% on each withdrawal. Run the embedded appreciation through that filter and the IRS collects $180,000 to $220,000 over the retirement horizon.

Net Unrealized Appreciation, explained in IRS Publication 575, lets her separate the employer stock from the rest of the plan. The $185,000 cost basis is taxed as ordinary income in the year of distribution, costing roughly $59,000 at a 32% marginal rate. The $695,000 of appreciation is taxed at long-term capital gains rates of 15% to 20% when shares are sold, with no holding period required for the original NUA gain. Sold immediately, the tax is $104,000 to $139,000.

Any NUA shares held until death pass to heirs with a stepped-up basis, erasing the embedded gain entirely for the next generation.

The Two Paths, Side by Side

Path 1: Roll everything to an IRA. Simple and frictionless, but the most expensive option for a holder of low-basis employer stock. Future required minimum distributions starting at age 73 will pull the appreciation out at ordinary rates.

Path 2: Elect NUA on the employer stock, roll the rest. In a single calendar year, she takes a lump-sum distribution of the entire $4.2 million balance. The $880,000 of employer stock transfers in-kind to a taxable brokerage account. The remaining $3.3 million rolls to an IRA in the same year. Miss the single-calendar-year requirement and the NUA election is permanently lost.

For most people in this position, Path 2 is the right answer.

Four Moves to Get This Right

1. Confirm the qualifying trigger and the calendar-year rule. NUA requires a lump-sum distribution of the entire 401(k) in one tax year, triggered by separation from service, reaching age 59½, death, or disability. Partial rollovers in the year before disqualify the election under IRS rules.
2. Get the 1099-R coding right. The plan administrator must report the cost basis in Box 2a and use the correct distribution code so the NUA portion is identified. Request the plan’s NUA documentation in writing before the distribution.
3. Cherry-pick the low-basis lots. Plans typically allow lot selection inside the employer-stock subaccount. Apply NUA only to the lots with the lowest cost basis. High-basis lots should be rolled to the IRA, since the tax arbitrage on those shares is minimal.
4. Diversify gradually after the distribution. The 15% to 20% long-term capital gains rate applies whether she sells on day one or in year five. Selling roughly one-fifth of the position per year spreads the gain across multiple tax years and reduces single-stock risk on an $880,000 concentrated bet.

A fee-only CPA or CFP who handles the NUA mechanics could be a smart move for many retirees in this position.