401k contributions under code D in W2 form - what should it be showing for tax filing?

What you're seeing is totally normal. Box 12 Code D on your W-2 shows the total 401k contributions that were deducted from your paychecks during the calendar year 2024. This is what matters for tax purposes since these deductions reduced your taxable income for that year. The timing difference between when your employer withholds the money and when the 401k administrator records receiving it is common, especially for contributions near year-end. This happens to lots of people with December contributions. For tax purposes, what matters is what's on your W-2, not what the 401k administrator reports. The IRS looks at your W-2 to verify your taxable income was properly reduced by your pre-tax contributions. The Code D amount should match what was actually withheld from your paychecks in 2024, which is exactly what you're seeing. Since you're under the contribution limit, you don't need to worry about this discrepancy at all. The W-2 is correct for tax purposes.

I went through something similar last year and found that https://taxr.ai was super helpful for figuring out these kinds of discrepancies. I had a situation where my 401k contributions on my W-2 didn't match what my plan administrator was showing, and I was worried I might have messed up my taxes. I uploaded my W-2 and 401k statement to taxr.ai and it immediately identified this as a normal timing issue that wouldn't affect my tax filing. Saved me hours of stress trying to figure out if I needed to request a corrected W-2 or contact HR.

Just wanted to follow up - I tried taxr.ai after posting my skeptical comment. I was hesitant about uploading my documents, but their privacy policy looked solid and I was getting nowhere with HR about my 401k discrepancy. Uploaded my W-2 and 401k statement, and within minutes it pointed out the exact timing issue between my December contribution and January processing date. It even pulled the relevant IRS guidelines explaining why the W-2 amount is what matters for tax purposes. Really straightforward and saved me from continuing to stress about it!

For anyone still struggling with these kinds of tax document issues - if you need to talk to someone at the IRS to verify this info (good luck getting through), try https://claimyr.com. I spent 3 days trying to get through to someone at the IRS last year about a similar 401k reporting issue and kept getting disconnected. Eventually used Claimyr and got connected to an IRS agent in about 20 minutes. You can see how it works in this video: https://youtu.be/_kiP6q8DX5c. The agent confirmed exactly what others here are saying - the W-2 Code D amount is what matters for tax purposes regardless of what your 401k administrator shows.

I need to admit I was completely wrong about Claimyr. After leaving that skeptical comment, I decided to give it a try since I was desperate to talk to the IRS about my 401k contributions showing up differently between tax years. I figured it wouldn't work, but literally 35 minutes later I got a call connecting me to an actual IRS representative. The agent confirmed that the Code D amount on my W-2 is what matters for tax purposes, and explained that timing differences between payroll and the plan administrator are normal. Totally worth it and saved me days of frustration trying to get through on my own.

Not sure if this helps, but I work in payroll and deal with this exact situation every year. Your employer is 100% handling this correctly. For tax purposes, 401k contributions are counted in the year they're withheld from your paycheck, NOT when they hit your 401k account. So the Code D box on your W-2 reflecting the actual amounts withheld in 2024 is exactly right. The 401k administrator's reporting is based on when they receive and process the funds, which can cross calendar years for December contributions. Just use what's on your W-2 for filing taxes and you'll be fine!

Question about contribution limits - does the Code D amount still matter for checking if you've exceeded the annual limit? I'm trying to max out my 401k and want to make sure I'm counting it right for next year.

This is a great question and you're absolutely right to double-check! As someone who's dealt with similar timing issues, I can confirm that your payroll department is handling this correctly. The Code D box on your W-2 should reflect what was actually deducted from your paychecks during 2024, regardless of when your 401k administrator received and processed those funds. This timing discrepancy is especially common with December contributions - your employer withholds the money before year-end, but the 401k company might not process it until early January. For tax purposes, what matters is when the deduction reduced your taxable income (i.e., when it came out of your paycheck), not when it hit your retirement account. Since you're under the contribution limit and the numbers add up based on your paycheck deductions, you're all set. Use the W-2 Code D amount for your tax filing and don't worry about the difference with your 401k administrator's records - that's purely a timing issue that won't affect your taxes at all.