7 401k Rollover Mistakes That Cost You Money in 2026

The most expensive 401k rollover mistakes include missing the 60-day rollover deadline, triggering mandatory 20% withholding on indirect rollovers, rolling into the wrong account type, and paying unnecessary custodian fees. These errors can cost thousands in taxes, penalties, and lost growth — often permanently reducing your retirement balance. (Related: How Market Downturns Affect Annuity Options in 401k Rollovers: What Retirees Should Know) (Related: Hidden 401k Rollover Fees in 2026: 7 Essential Costs to Watch) (Related: Illinois 401k Rollover Tax Rules 2026: The Complete Guide) (Related: 401(k) Rollover Options: Understanding Crypto IRAs, Rules, and Risk Assessment) (Related: 401k Rollover While Still Employed: The Complete 2026 Guide) (Related: How Proposed Roth IRA Rollover Legislation Affects Your Retirement Strategy – Analysis and Calculator Guide)

Deadline and Distribution Mistakes

The IRS gives you exactly 60 days to complete an indirect rollover once you receive a distribution. Miss that window by even one day, and the entire amount becomes taxable ordinary income in the year received. If you’re under age 59½, a 10% early withdrawal penalty applies on top of that income tax.

What makes this worse is the mandatory 20% federal withholding rule. When your employer cuts you a check directly — rather than sending funds to your new custodian — they’re required to withhold 20% for taxes. To complete a full rollover and avoid taxes on that withheld amount, you must deposit 100% of the original balance using your own money to cover the withheld portion. Most people don’t realize this until it’s too late.

How to avoid it: Always request a direct rollover (also called a trustee-to-trustee transfer). Your old plan sends funds directly to your new IRA or employer plan. You never touch the money, no withholding applies, and there’s no 60-day deadline risk.

Use our Early Withdrawal Penalty Calculator to see exactly how much a missed deadline or accidental distribution could cost you in taxes and penalties.

Rolling Into the Wrong Account Type

Not every rollover destination is created equal, and choosing the wrong account type creates immediate, sometimes irreversible tax consequences.

Pre-Tax Funds Into a Roth IRA

Rolling traditional 401k money (pre-tax contributions and earnings) into a Roth IRA is technically allowed, but the entire converted amount becomes taxable income in the year of the rollover. This is called a Roth conversion, not a standard rollover. If you have $200,000 in a traditional 401k and roll it into a Roth IRA without planning for the tax bill, you could owe $40,000–$60,000 or more in federal income taxes, potentially in one lump sum.

After-Tax Contributions Rolled Incorrectly

Some 401k plans accept after-tax (non-Roth) contributions. These have a cost basis, meaning that portion isn’t taxed again at rollover — but only if you handle it correctly. Rolling after-tax contributions into a traditional IRA alongside pre-tax money complicates the pro-rata rule and may cause unnecessary taxation later.

Before choosing a destination account, compare the cost difference between account types using our Traditional vs Roth IRA Calculator.

Ignoring Fees Charged by Custodians

Custodian fees don’t disappear after you roll over — in many cases, they increase. Common fees to watch for include:

Outgoing rollover fees: Your old 401k plan may charge $50–$150 to process the distribution.
IRA annual maintenance fees: Some IRA custodians charge $25–$75 per year, or more for smaller balances.
Fund expense ratios: Moving from low-cost institutional funds in a 401k to retail mutual funds in an IRA can increase your expense ratio from 0.03% to 0.80% or higher annually.
Account closing fees: Charged when you exit a custodian entirely, typically $50–$100.

A fee difference of 0.5% per year on a $150,000 balance compounds to over $40,000 in lost growth over 25 years. Always request a complete fee schedule from both your old plan and your new custodian before initiating any rollover. Check if your new IRA offers fee waivers for larger rollover amounts — many custodians waive annual fees above a certain balance threshold.

See how fees affect long-term growth with our 401k Growth Calculator.

Rollover Timing and Process Errors

The One-Rollover-Per-Year Rule

The IRS limits you to one indirect IRA-to-IRA rollover every 12 months, across all your IRAs combined — not per account. Violating this rule means the second rollover is treated as a taxable distribution, subject to income tax and potentially a 10% early withdrawal penalty. Direct trustee-to-trustee transfers are not subject to this limit, which is another reason to use them whenever possible.

Rolling Into an Active Employer Plan Incorrectly

If you’re rolling your old 401k into a new employer’s 401k plan, the new plan must accept incoming rollovers — not all plans do. Rolling pre-tax money into a plan that only accepts after-tax contributions, or vice versa, creates a taxable event. Confirm rollover acceptance and the plan’s specific procedures in writing before submitting any paperwork.

Missing Required Minimum Distributions Before Rolling Over

If you’re age 73 or older and still have money in a 401k, you must take your Required Minimum Distribution (RMD) for the year before completing a rollover. RMD amounts are never eligible for rollover — rolling an RMD amount into an IRA is treated as an excess contribution, which triggers a 6% penalty on that amount each year it remains in the account.

Calculate your RMD before initiating a rollover using our RMD Calculator.

Use Our Free Calculators to Estimate Your Rollover Costs

Before moving your retirement money, run the numbers. These free tools help you understand exactly what a rollover will cost — and what mistakes could cost you.

401k Rollover Calculator — Estimate taxes, fees, and net rollover amounts based on your specific balance and situation.
Early Withdrawal Penalty Calculator — See the full cost of a missed deadline or accidental cash-out, including federal and state taxes plus penalties.
401k Growth Calculator — Understand how fee differences between your current plan and a new IRA affect long-term balance growth.

Frequently Asked Questions

What happens if I miss the 60-day rollover deadline?

The distributed amount becomes fully taxable ordinary income in the year received. If you’re under 59½, you also owe a 10% early withdrawal penalty. In limited hardship cases, the IRS may grant a waiver, but these are not automatic and require documentation.

How much does a 401k rollover typically cost in fees?

Outgoing rollover fees from a 401k plan range from $0 to $150. New IRA custodians may charge $0 to $75 annually. The largest cost is usually the difference in investment expense ratios between your old plan’s institutional funds and retail funds available in an IRA.

Do I owe state taxes on a 401k rollover?

A properly completed direct rollover is not a taxable event at the state level either. However, if funds are distributed to you and not redeposited within 60 days, state income taxes apply in addition to federal taxes. Rates vary significantly — from 0% in states with no income tax to over 13% in high-tax states.

Can I roll over a 401k while still employed?

Most 401k plans only allow rollovers after you’ve left the employer. However, some plans offer “in-service distributions” at age 59½ or older. Check your Summary Plan Description or contact your plan administrator to confirm whether in-service rollovers are permitted.

What’s the difference between a rollover and a transfer?

A rollover involves receiving a distribution and redepositing it into another retirement account (subject to the 60-day rule and one-per-year limit). A transfer (trustee-to-trustee) moves funds directly between institutions without you receiving them — no withholding, no deadline risk, and no annual limit.

Written by James Whitfield | Updated April 2026 | For educational purposes only. Always consult a qualified financial professional before making retirement decisions.