Retirement Calculator
Dormant 401(k) Rollover Decision Tool: What It Calculates and How to Read the Result
Quick answer
Rolling an old 401(k) to an IRA gives you broader investment choice and unified account management, but it gives up some 401(k)-specific benefits: stronger federal creditor protection, the rule of 55 for early withdrawals, and (most importantly) the Net Unrealized Appreciation (NUA) treatment for highly appreciated employer stock. The right answer depends on which features apply to your situation.
What This Calculator Actually Answers
This decision tool walks you through the four variables that determine whether to roll over a dormant 401(k): the expense ratios of your current plan investments versus what's available in an IRA, the presence of highly appreciated employer stock (where NUA treatment can be worth six figures of tax savings), outstanding 401(k) loans (which become taxable distributions if you separate without repaying), and your age relative to the rule of 55 window.
The output gives you a recommendation framework, not a single answer. For most former employees with a clean 401(k) (no employer stock, no outstanding loans, average plan expense ratios), the case for rolling to a self-directed IRA is strong. For employees with concentrated employer stock or who plan to retire between 55 and 59½, the decision is genuinely complicated.
How to Read the Result
Net Unrealized Appreciation (NUA) is the single largest variable in this decision. If you have employer stock that has appreciated significantly inside the 401(k), distributing the stock in-kind to a taxable brokerage account (rather than rolling it into an IRA) means you pay ordinary income tax only on the original cost basis. The appreciation is then taxed at long-term capital gains rates when you sell, typically a 15–25 percentage-point savings on the appreciation portion. Once you roll the stock into an IRA, NUA is permanently lost.
The rule of 55 allows penalty-free withdrawals from a 401(k) starting in the year you turn 55 if you separate from that employer. IRAs do not have this rule (they require 59½). If you are planning to retire between 55 and 59½ and will need access to the dormant 401(k) during that window, rolling it to an IRA gives up the rule of 55.
Common Mistakes
- Rolling employer stock into an IRA without evaluating NUA. This is one of the most expensive irreversible decisions in retirement planning, and the form your old plan sends you does not flag it.
- Leaving an old 401(k) in a plan with high expense ratios (>0.40%) when an IRA could deliver the same exposure at 0.05% or less, costing thousands per year in unnecessary fees.
- Forgetting that outstanding 401(k) loans become taxable distributions (with a 10% penalty if under 59½) when you separate from the employer without paying them back.
- Rolling over without evaluating whether your IRA balance will affect the pro-rata rule on future backdoor Roth contributions.
- Doing an indirect (60-day) rollover instead of a direct trustee-to-trustee transfer: the 20% mandatory withholding on indirect rollovers creates a tax mess most people don't anticipate.
When This Calculator Is Not the Right Tool
This tool handles the rollover decision in isolation. It does not model your full retirement income strategy or coordinate with Roth conversion planning. If you have a $500K+ 401(k) and are within 10 years of retirement, the rollover decision should be made as part of a broader plan that addresses withdrawal sequencing and pre-RMD Roth conversion strategy.
Frequently Asked Questions
Is there a tax cost to rolling a 401(k) to an IRA?
No, a direct trustee-to-trustee rollover of a traditional 401(k) to a traditional IRA is non-taxable. A rollover of a Roth 401(k) to a Roth IRA is also non-taxable. The 60-day indirect rollover route creates a 20% mandatory withholding that you have to replace from other funds to avoid taxation — most people should use direct transfers.
What is NUA and when does it apply?
Net Unrealized Appreciation (NUA) is a special tax treatment for employer stock held inside a 401(k) at distribution. You pay ordinary income tax on the original cost basis at distribution, then the appreciation is taxed at long-term capital gains rates when you eventually sell the shares (held in a regular brokerage account). NUA only applies in a 'lump-sum distribution' year, typically the year you retire or separate. Once you roll the stock into an IRA, NUA is permanently lost.
Does rolling over affect my ability to do backdoor Roth contributions?
Yes, rolling a traditional 401(k) into a traditional IRA adds to the pre-tax IRA balance the pro-rata rule applies to. If you do (or plan to do) backdoor Roth contributions, that pro-rata balance becomes a material tax issue. Some employees leave the 401(k) in place specifically to preserve the backdoor Roth pathway; others reverse the calculation by rolling the IRA balance back into a current 401(k) (if the plan accepts incoming rollovers).
How much does the rule of 55 actually matter?
Only if you plan to retire between ages 55 and 59½ and will need penalty-free access to that 401(k) during that window. If you have enough other assets (Roth contributions you can withdraw without penalty, taxable brokerage, an HSA) to bridge to 59½, the rule of 55 is largely irrelevant.