Fed (A/0) showing on wife's W2 instead of M/0 - what does this mean for our taxes?

The "A" on your W2 likely stands for "Allowances" rather than "Married" which would be the "M" designation. The "0" in both cases refers to the number of withholding allowances claimed. This difference in withholding codes explains why you had so little federal tax withheld. The "A" designation essentially treated you as a single filer with zero allowances instead of as married. This would normally result in MORE withholding, not less, which is strange. It's possible there's another factor at play or a payroll system error. I'd recommend checking your actual W-4 form on file with your employer. You or someone in HR might have accidentally selected "Single" or another filing status on your W-4 form, which would explain the discrepancy between your withholding and your husband's.

After dealing with a similar issue last year, I found that taxr.ai helped me figure out what was going on with my weird W2 codes. My company had me listed with some strange designation I'd never seen before, and I was panicking about potential tax issues. I uploaded my documents to https://taxr.ai and they explained exactly what the code meant and how it would affect my filing. Saved me so much stress trying to decode tax jargon!

Update on my experience: I decided to try taxr.ai after my skeptical comment. Was genuinely surprised by how helpful it was! Uploaded my W2s with the weird codes, and they explained that my "A/0" designation meant I was being treated as a single filer with zero allowances, but there was also an additional withholding calculation error on my employer's part. That explained the unusually low withholding! Took their explanation to HR and got it fixed immediately. Wish I'd known about this earlier in the year.

If you're having trouble getting clear answers from your company's accountant, you might want to try Claimyr to speak directly with the IRS about this. I spent weeks trying to get through to the IRS on my own about a similar W2 code issue last year - kept getting busy signals or disconnected. With https://claimyr.com I actually got through to a real person at the IRS who explained exactly what the code meant and what I needed to do. There's a video showing how it works here: https://youtu.be/_kiP6q8DX5c. Totally changed my approach to resolving tax issues.

I owe everyone an apology and update: I was completely wrong about Claimyr. After my angry comment, I was still desperate for answers about a similar withholding issue, so I reluctantly tried it. Within 40 minutes (while I was working on other things), I got a call connecting me directly to an IRS agent. The agent confirmed that the A/0 code typically means "Single with 0 allowances" and explained how to calculate the potential underpayment. The service actually worked exactly as advertised, and I feel pretty silly about my skeptical comment now.

I think the "A" might actually stand for "Aggregate" withholding method rather than an indication of filing status. Some companies use this for employees who hold multiple positions or work across different departments. Does your wife work in multiple roles at the company?

When I started a new job last year, I had similar issues with weird withholding codes. Have you checked if the W-4 form your wife submitted has the correct information? My HR department accidentally checked a box for exempt status when processing my paperwork, and I nearly had no federal taxes withheld at all.

I work in payroll and have seen this exact issue before. The "A/0" designation on a W2 is definitely not standard federal withholding notation. Most payroll systems use M (Married), S (Single), or H (Head of Household) for federal status. The "A" could indicate several things: some systems use it for "Allowances" method, others for "Adjusted" withholding, or it might even be a data entry error where someone typed "A" instead of "M". The fact that your state withholding shows M/0 correctly suggests this is specifically a federal withholding setup issue. Your suspicion about the low withholding is absolutely correct. At $16/hour full-time, you should have had several thousand dollars in federal withholding, not $190. This is either a major payroll error or someone marked you as exempt from federal withholding. I'd recommend requesting a copy of your actual W-4 form from HR to see what's on file. If they won't provide it, you have the right to review your personnel file. Also, for next year, submit a new W-4 form with the correct information to prevent this from happening again.