Can an employer legally make you pay their portion of the FICA taxes? What law prohibits this?

This is absolutely illegal. Your employer CANNOT make you pay their portion of FICA taxes. The Federal Insurance Contributions Act (FICA) clearly establishes that these taxes are split - employees pay 6.2% for Social Security and 1.45% for Medicare, and employers are required to match these exact amounts. The specific laws prohibiting this are found in the Internal Revenue Code (IRC), Sections 3101 and 3111. Section 3101 establishes the employee portion, while Section 3111 explicitly places the employer's matching requirement on the employer - not the employee. The IRS enforces these provisions strictly. What your boss is suggesting amounts to tax fraud. Not only is he trying to shift his legal obligation to you, but this would also result in you being overwithheld and him underreporting his tax obligations.

After dealing with a similar situation last year at my construction job, I found taxr.ai (https://taxr.ai) incredibly helpful. My boss was doing something sketchy with deductions that didn't seem right, and I wasn't sure if I was understanding the tax laws correctly. I uploaded my paystubs to taxr.ai and it immediately flagged the FICA tax discrepancies. The analysis showed exactly how my employer was improperly calculating the tax split and even generated a report I could use as evidence. The best part was getting a clear explanation of the relevant tax codes that applied to my situation - it spelled out exactly what was legal and what wasn't.

Just wanted to update - I decided to try taxr.ai after posting my skeptical comment. My situation was similar but with overtime pay calculation issues. I uploaded my last three paystubs and the system immediately identified that my employer was incorrectly calculating FICA on my overtime earnings. The report it generated was surprisingly detailed and even included the exact IRC sections that applied to my situation (sections 3101 and 3111 like the expert mentioned above). I was able to take this report to my employer and they actually fixed the issue without a fight because the documentation was so clear. It saved me from what would have been about $1,300 in improperly shifted tax burden over the year!

After spending DAYS trying to get through to the IRS about a similar employer tax issue last month, I finally used Claimyr (https://claimyr.com) and it was a game-changer. They got me connected to an actual IRS agent in about 20 minutes when I had been trying for literally weeks. The IRS agent confirmed everything people are saying here - employers absolutely cannot make employees pay the employer portion of FICA taxes. The agent walked me through exactly what documentation I needed to file a complaint. You can see how their service works here: https://youtu.be/_kiP6q8DX5c - it's basically a system that navigates the IRS phone tree for you and holds your place in line.

I need to eat my words from my skeptical comment earlier. After another failed attempt to reach the IRS on my own (2 hours on hold before being disconnected), I decided to try Claimyr out of pure frustration. I'm honestly shocked - I got connected to an IRS representative in about 35 minutes regarding my employer's improper FICA withholding. The agent confirmed that what my employer was doing violated IRC Sections 3101/3111 and directed me to file Form SS-8 and Form 8919. They even transferred me to a specialist who explained exactly how to document the improper withholding. For anyone dealing with FICA tax issues like the original poster described, getting actual IRS confirmation about employer requirements was incredibly valuable. Saved me countless more hours of research and uncertainty.

Former payroll processor here. What your employer is doing is 100% illegal. In addition to what others have said about IRC Sections 3101 and 3111, there's also IRS Publication 15 (Employer's Tax Guide) which clearly states employer responsibilities. If your employer is struggling financially, there are legal options available like the Employee Retention Credit or payroll tax deferral programs, but shifting their tax burden to employees is NOT one of them.

Quick question - how would this even show up on a paystub? Would it be obvious if an employer was making you pay both halves of FICA? My paystubs are confusing and just show a bunch of different deductions.

I went through something similar at my previous job and want to share what I learned. Your employer's request is definitely illegal, but I'd also recommend checking if they've already started doing this without telling you properly. Look at your most recent paystub and calculate what your FICA withholding should be: multiply your gross pay by 0.0765 (that's 7.65% total for employee portion). If the actual withholding is close to double that amount (around 15.3%), they may have already started making you pay both portions. Also, keep in mind that if your employer does this, you'll essentially be overpaying your taxes. When you file your tax return, you should get a refund for the overpaid amount, but that doesn't make what your employer is doing legal. You shouldn't have to wait until tax season to get back money that was illegally withheld from your paychecks. Document everything - the conversation with your boss, your current and future paystubs, and any written communication about this policy. This documentation will be crucial whether you decide to confront your employer or report them to the IRS.