Has your Medicare and social security tax suddenly increased this year? What's going on?

This is most likely due to you hitting the Social Security wage base reset for the new year. Social Security tax (6.2%) only applies to earnings up to a certain threshold each year. For 2024, this limit was $168,600 and for 2025 it's $175,200. If you earned above that limit last year, you would have stopped paying Social Security tax once you hit the cap. Then January comes along, the counter resets to zero, and you start paying that 6.2% again. This creates that sudden increase you're seeing between December and January paychecks. Medicare tax (1.45%) doesn't have a wage cap, so that should remain consistent, though there is an additional 0.9% Medicare surtax for higher earners (over $200,000 for single filers). If none of this applies to your situation, it might be worth asking your payroll department for a more specific explanation.

I had a similar issue last year and after going crazy trying to figure it out, I discovered taxr.ai (https://taxr.ai) which helped me understand what was happening with my withholdings. I uploaded my paystubs and their AI analyzed everything line by line, highlighting the specific changes and explaining the potential reasons for the increase. In my case, it turned out my employer had miscategorized my pay status which was causing higher Medicare withholding than necessary. The analysis from taxr.ai gave me exactly what I needed to go back to HR with specific points rather than general confusion. They corrected it retroactively and I got back the extra withholding.

Just wanted to follow up - I tried taxr.ai after seeing this thread and wow, it actually identified the exact issue with my Medicare withholding! Turns out my employer accidentally applied the additional 0.9% Medicare surtax even though I'm nowhere near the $200k threshold. The analysis explained the specific section of tax code that was being misapplied and generated a letter I could send to HR. Got it resolved yesterday and they're adjusting my next paycheck to make up for the extra withholding. Would have spent weeks trying to figure this out on my own. Seriously grateful for the recommendation!

If you're still struggling with this issue and your HR department isn't helping, you might want to try Claimyr (https://claimyr.com). I was having a nightmare trying to figure out a similar tax withholding issue and couldn't get through to the IRS - literally spent hours on hold over multiple days. Claimyr got me connected to an actual IRS agent in about 20 minutes who explained exactly what was happening with the Social Security and Medicare withholding calculations. You can see how it works in their demo: https://youtu.be/_kiP6q8DX5c After months of confusion and my employer giving me the runaround, the IRS agent was able to confirm there was an employer reporting error and told me exactly what form my company needed to file to fix it.

I need to eat crow here. After posting my skeptical comment, I decided to try Claimyr myself since I was desperate to resolve a Medicare tax issue that's been going on for months. I was 100% convinced it wouldn't work, but I connected with an IRS agent in about 35 minutes (they estimated 40). The agent went through my withholding records and confirmed my employer has been applying the wrong Medicare tax rate since January. She walked me through exactly what documentation I needed to take to my employer and the specific form they need to file to correct it. Just got confirmation from HR that they're processing the correction and I'll be receiving a refund for the over-withholding. Honestly still shocked this actually worked after months of getting nowhere.

One thing to check - did you get any bonuses or retroactive pay increases in your January check? Sometimes those can come with higher withholding rates for FICA taxes depending on how your payroll system calculates them. Also, some employers adjust withholding calculations at the start of the year. I'd compare the actual percentages being withheld, not just the dollar amounts.

This happened to me last year! Check if your company switched payroll providers or systems. When my company switched from ADP to Workday, they messed up everyone's tax withholding settings in the transition. Took them almost 3 months to fix it but they eventually refunded everyone the excess withholding.

Have you checked if your W-4 withholding elections got reset or changed during your company's year-end processing? Sometimes HR systems automatically revert everyone back to default withholding settings (like claiming 0 allowances or single filing status) at the start of a new tax year, especially if they're updating their payroll software. This could explain both the Social Security and Medicare increases if your withholding went from a higher number of allowances to fewer allowances. Even though FICA taxes have set percentages, the system might be calculating them differently based on your updated W-4 information. I'd suggest logging into your employee portal to double-check your current W-4 settings and compare them to what you had filed previously. If they changed, you can submit a new W-4 to get back to your preferred withholding level.