Yes, you report 401(k) contributions and withdrawals on your tax return, but the way you report them depends on whether your plan is traditional or Roth

If you have a traditional 401(k), your employer withholds taxes from your paycheck before the money goes into the account, and your W-2 form already reflects this. You do not file a separate form to report the contribution itself — it shows up on your W-2 as part of your gross income calculation. However, when you withdraw money from the account, you must report that withdrawal on your tax return.

If you have a Roth 401(k), you contribute after-tax dollars, meaning you already paid income tax on the money. Your contributions do not reduce your taxable income, and withdrawals of your contributions are not taxed again. Roth contributions also appear on your W-2, but they are listed separately so the IRS knows they were made with after-tax money.

The key difference: traditional contributions lower your taxable income in the year you make them, while Roth contributions do not. Both types require you to report withdrawals when you take money out.

Key Takeaways

  • Your employer reports 401(k) contributions on your W-2 form, so you do not file a separate form just to report that you contributed.
  • Withdrawals from a traditional 401(k) must be reported on your tax return as income, and you owe income tax on the full amount withdrawn.
  • Withdrawals from a Roth 401(k) are not taxed if you follow the rules (age 59½ or older, account open at least five years), but you still report them on your return.
  • If you withdraw money before age 59½ from a traditional 401(k), you owe a 10 percent early withdrawal penalty on top of income tax, unless an exception applies.
  • The IRS sends you a Form 1099-R each January for any 401(k) withdrawal you made the previous year, and you use this form to complete your tax return.

How your W-2 handles 401(k) contributions

Your employer files a W-2 form with the IRS each January showing what you earned and what was withheld. Box 1 on the W-2 shows your taxable wages after 401(k) contributions have been subtracted. This means the IRS already knows about your traditional 401(k) contributions — they are baked into the W-2 calculation.

You do not need to file Form 8606 or any other special form just because you contributed to a 401(k). The W-2 does the reporting for you. When you file your tax return, the software or tax preparer pulls the W-2 information directly into the return, and the contribution is already accounted for.

Roth 401(k) contributions appear on the W-2 as well, but in a separate box (usually Box 12 with code AA). This tells the IRS that part of your income was set aside as Roth, which means it was not deducted from your taxable income.

Reporting withdrawals using Form 1099-R

When you withdraw money from a 401(k) — whether traditional or Roth — your plan administrator sends you a Form 1099-R by January 31 of the following year. This form shows the total amount withdrawn and how much federal tax was withheld from the withdrawal.

You must report this 1099-R on your tax return. The form goes into the income section of your return, and the IRS receives a copy as well. If you do not report it, the IRS will notice the mismatch between what the plan reported and what you filed.

The 1099-R also includes a code that describes the type of withdrawal — for example, code 1 means you were age 59½ or older, code 2 means you were younger and owe a penalty, and code 7 means it was a distribution for a specific reason like disability. This code helps the IRS determine whether you owe the 10 percent early withdrawal penalty.

Traditional 401(k) withdrawals and income tax

Money you withdraw from a traditional 401(k) is taxed as ordinary income in the year you withdraw it. If you withdraw $10,000, you report $10,000 as income on your tax return, and you owe income tax at your regular tax rate (which depends on your total income for the year).

Your plan administrator withholds a percentage of the withdrawal for federal income tax — usually 20 percent for lump-sum withdrawals, though you can request a different amount. This withholding is not the final tax you owe; it is just a payment toward your tax bill. When you file your return, the IRS calculates your actual tax liability. If more was withheld than you owe, you get a refund. If less was withheld, you owe the difference.

If you withdraw money before age 59½, you also owe a 10 percent early withdrawal penalty on top of the income tax, unless you meet an exception. Common exceptions include withdrawals for a first-time home purchase (up to $10,000 lifetime), medical expenses that exceed 7.5 percent of your adjusted gross income, or disability. The 1099-R code will indicate whether a penalty applies.

Roth 401(k) withdrawals and the five-year rule

Roth 401(k) withdrawals follow a different tax rule. If you are age 59½ or older and your account has been open for at least five years, withdrawals are tax-free. You still report the withdrawal on your tax return, but none of it is taxable income.

If you withdraw money before age 59½, or if your account has been open for fewer than five years, the earnings portion of the withdrawal is taxed as income and may be subject to the 10 percent early withdrawal penalty. Your contributions (the money you put in) can always be withdrawn tax-free, but the earnings are treated differently.

The 1099-R for a Roth withdrawal will show the total amount, but it may not clearly break down how much is contributions versus earnings. You may need to contact your plan administrator to get this breakdown, or you can calculate it yourself using your plan records.

Required minimum distributions and reporting

Once you reach age 73 (as of 2023; this age changes under current law), you must begin taking required minimum distributions (RMDs) from your traditional 401(k) each year. The amount is calculated based on your age and account balance. These distributions are reported on a 1099-R just like any other withdrawal, and you owe income tax on them.

If you do not take your RMD, the IRS imposes a penalty of 25 percent of the amount you should have withdrawn (reduced to 10 percent if you correct it within two years). This penalty is separate from income tax and is reported on Form 5329, which you file with your tax return.

Roth 401(k)s do not require minimum distributions during your lifetime, but they do after your death if the account passes to a beneficiary. Your plan administrator will guide you on the rules for your specific situation.

What to do if you did not receive a 1099-R

If you withdrew money from a 401(k) but did not receive a 1099-R by early February, contact your plan administrator first. They may have sent it to an old address, or the withdrawal may not have been processed yet. Ask them to resend it or provide a corrected form.

If you still cannot locate the form, you can file your tax return without it, but you must report the withdrawal amount based on your own records. Keep documentation of the withdrawal (bank statements, plan statements, or correspondence from the plan) in case the IRS asks questions later.

If the plan administrator made an error on the 1099-R — for example, reporting the wrong amount — ask them to issue a corrected form (Form 1099-R with "CORRECTED" printed on it). You then file the corrected form with your tax return and keep a copy for your records.

Frequently Asked Questions

Do I have to report my 401(k) balance on my tax return?

No. You only report contributions (which appear on your W-2) and withdrawals (which appear on a 1099-R). The balance sitting in your account is not reported to the IRS unless you withdraw it.

What if my employer made a matching contribution to my 401(k)?

Employer matching contributions are treated the same as your own contributions. They reduce your taxable income on your W-2 and are not reported separately on your tax return. They are already accounted for in Box 1 of your W-2.

Can I deduct 401(k) contributions on my tax return if my employer did not take them out of my paycheck?

If you made catch-up contributions or after-tax contributions outside the normal payroll process, your plan administrator should report them on your W-2 or provide documentation. You do not file a separate form; the contributions appear on your W-2. If there is a discrepancy, contact your plan administrator to correct it before filing.

Do I owe taxes on 401(k) earnings while the money is still in the account?

No. In a traditional 401(k), earnings grow tax-deferred, meaning you do not owe tax on them until you withdraw the money. In a Roth 401(k), earnings grow tax-free and are never taxed if you follow the withdrawal rules. You only owe tax when you actually take money out.

What if I rolled my 401(k) into an IRA?

A direct rollover (where the plan sends the money straight to the IRA) is not a taxable event and does not require you to report anything special on your tax return. If you did an indirect rollover (the plan sent you a check), you have 60 days to deposit it into an IRA, and you must report the transaction on Form 8606 if it was a Roth conversion. Your plan will send a 1099-R either way, so report it as a rollover on your return.