If I roll my 401(k) into a Roth IRA, which part of the balance gets taxed?

By Kaz · Published 28 September 2026 · How this site checks figures

Summary

Only the money that has never been taxed. That's all of it for ordinary pretax 401(k) money, none of it for Roth 401(k) money, and for after-tax contributions only the earnings on them. A direct rollover has nothing withheld, so the tax on the taxable part is settled when you file for the year of the rollover.

Source by source

What's in the 401(k)	Taxable when it goes into a Roth IRA
Pretax money, the ordinary 401(k) balance	All of it
Roth 401(k) contributions and earnings, direct rollover	None
After-tax (non-Roth) contributions	None
Earnings on those after-tax contributions	All of it; the IRS treats them as pretax

The plan's Form 1099-R reports the same split. For a direct rollover of non-Roth 401(k) money to a Roth IRA, the IRS instructions put the total in box 1, the taxable amount in box 2a and any after-tax basis in box 5, with code G. For Roth 401(k) money going to a Roth IRA, box 2a is zero and the code is H.

A plan with after-tax money in it

The IRS's example is a $100,000 balance: $80,000 pretax and $20,000 after-tax. If you take the whole balance, you can send the $80,000 directly to a traditional IRA or another plan's pretax account and the after-tax money to a Roth IRA. Split that way, nothing going into the Roth IRA is taxable. Send all $100,000 to the Roth IRA instead and the $80,000 pretax share is income for the year.

What you can't do is take out just the after-tax dollars. "Any partial distribution from the plan must include some of the pretax amounts," so a $50,000 withdrawal from the same account comes out as $40,000 pretax and $10,000 after-tax. The guide to splitting pretax and after-tax money covers how to set up the two destinations.

When the Roth 401(k) check comes to you first

A nonqualified Roth 401(k) distribution paid to you is taxable only in its earnings, and a 60-day rollover of part of it is applied to the earnings first. In the IRS's example, Bob receives a $14,000 nonqualified distribution, $11,000 of it contributions and $3,000 earnings, and rolls $7,000 into a Roth IRA within 60 days. The rolled-over amount is treated as the taxable part first, so the $7,000 counts as the $3,000 of earnings plus $4,000 of contributions, and none of the distribution is included in Bob's income.

No withholding, and no undo

Topic 413 says mandatory withholding "doesn't apply in a direct rollover," which means a Roth rollover of $60,000 in pretax money puts all $60,000 in the Roth IRA and leaves the tax on it for your return. The move is also permanent. Since January 1, 2018, amounts rolled into a Roth IRA from a 401(k) or 403(b) can't be recharacterized as a traditional IRA contribution.

Sources

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