From my understanding, you don't actually need to file an amendment if the only issue is that you didn't report qualified HSA distributions. The IRS usually only cares if you took non-qualified distributions that should have been taxed.

I went through this exact same situation last year! The key thing to remember is that you absolutely need to file Form 1040X with Form 8889 attached, even if all your HSA distributions were for qualified medical expenses. Here's what helped me navigate this process: 1. Gather all your medical receipts from 2024 that total at least $533.11 (your distribution amount) 2. Form 8889 will calculate whether your distributions were qualified or not 3. If they were all qualified medical expenses, your tax liability won't change - you're just documenting the distributions properly The amendment process isn't as scary as it seems. You'll need to mail the 1040X (electronic filing isn't available for most amendments), but the IRS typically processes them within 16-20 weeks. Since you used Credit Karma, you can download your original return as a PDF and use that to fill out the 1040X manually. Focus on getting Form 8889 right - that's the critical piece for HSA reporting. The IRS has good instructions on their website for Form 8889 that walk through the HSA distribution reporting step by step. Don't wait too long to file the amendment - it's better to be proactive than wait for the IRS to notice the discrepancy between your 1099-SA and your return!

One thing nobody mentioned - make sure the information on your 1095-C is actually correct! My employer had me listed with coverage for months I wasn't employed there and it caused a huge headache. Check the coverage months in Part II to make sure they match when you actually had the insurance.

Just to add another perspective - if you're someone who frequently switches between different health insurance plans or has gaps in coverage, the 1095-C becomes more important for your records. Even though TurboTax doesn't ask for it directly, having this form helps you track your coverage timeline, especially if you need to reconcile any Premium Tax Credits you received through the marketplace. I learned this the hard way when I had overlapping employer coverage and marketplace coverage for a few months. The 1095-C helped me sort out which months I was covered by what plan when the IRS had questions later.

Quick question - if OP changes their W-4 now to withhold a bunch of extra money from their last few 2025 paychecks, will that actually help with the underpayment penalty? I thought the penalty was calculated by quarter, so fixing it in December wouldn't help with the earlier quarters when nothing was withheld?

I actually just went through this exact same situation earlier this year! Made the same mistake with the exemption box and didn't notice for months. Here's what I learned: First, don't panic - this is more fixable than you think. The key thing to understand is that withholding from your paycheck gets treated as if it was paid evenly throughout the year, even if you do it all in December. This is huge because it can help with penalties retroactively. I'd strongly recommend doing BOTH things mentioned above - submit a new W-4 with maximum additional withholding for your remaining paychecks AND make a Q4 estimated payment if needed. Calculate roughly what you'll owe for the full year, subtract what was already withheld from your first job, then split the remainder between increased withholding and estimated payment. Also look into first-time penalty abatement if you haven't had issues before - it can waive penalties entirely if you qualify. The IRS is actually pretty reasonable about honest mistakes like this, especially if you're proactive about fixing it before filing. One last tip: when you do your W-4 next year, maybe set it to withhold slightly more than needed so you have a buffer. Better to get a small refund than deal with this stress again!

Quick question about this EITC situation - does anyone know if TurboTax handles this correctly? Like if I input that I have 50/50 custody and want to claim EITC for a kid that my ex is claiming as a dependent, will it let me do that or will it give me an error?

I just went through this exact situation last year! Your tax preparer is absolutely right - EITC and dependency claims operate under different rules. I had 50/50 custody with my ex, and I was able to claim EITC for both kids even though we alternated who claimed them as dependents each year. The key thing to remember is that EITC is based on the "qualifying child" test, which looks at things like where the child lived for more than half the year. With true 50/50 custody, either parent could potentially claim EITC if they meet the income requirements. Since your ex makes too much to qualify for EITC anyway, there's no conflict. Your ex's return won't be rejected - the IRS systems don't automatically cross-reference EITC claims with dependency claims in the way you might think. Just make sure you have documentation of your custody arrangement and that all the child's information (SSN, name spelling, etc.) is consistent on both returns. One tip: I found it helpful to give my ex a heads up about the arrangement just to avoid any confusion or concern on their end when they saw different credits being claimed. Good communication goes a long way in co-parenting situations, especially around tax time!

Here's a small tip - if you do end up owing an underpayment penalty, ask for First Time Penalty Abatement! The IRS will often waive penalties the first time you have an issue if you've had a good compliance history (filed and paid on time) for the past 3 years.

As someone who went through this exact situation last year, I can tell you that you're probably overthinking this! The fact that nothing is showing in your IRS account is actually a good sign - they're usually pretty quick to post penalties when they apply them. For your withholding question, yes absolutely! Adjusting your W-4 is actually the smartest approach. The IRS treats payroll withholding as if it happened evenly throughout the year, which gives you a huge advantage over quarterly payments. Even if you increase your withholding in December, they treat it as if you paid that amount in four equal installments starting in January. Just calculate roughly 22-24% of your expected interest income (depending on your tax bracket) and divide that by your remaining pay periods. Submit a new W-4 with that additional amount. Way easier than remembering quarterly due dates! One more thing - keep all your 1099-INT forms organized. Next year you'll have a better sense of what to expect and can adjust your withholding at the beginning of the year instead of scrambling at the end.