Since I posted my question I have gotten access to my pay statements for 2024 (my former employer was acquired by another company mid-2024 so this complicated the situation). I was able to determine, based on these pay statements, that the large discrepancy was due to a change made in the payroll system when I requested that withholding be stopped mid-year. For some unknown reason, the wages post stopping withholding were marked as not subject to federal income tax when in fact they WERE subject to federal income tax.
Based on my pay statements I was able to do the calculations (gross wages + group term life - pretax deductions) and tell the former employer what number SHOULD be in Box 1. After I told the former employer I had contacted the IRS (which I did but was a waste of time) and that the IRS would contact them and tell them they had 10 days to provide a corrected W-2 the former employer contacted the payroll software support line and I was provided a W2C the next day.
Thanks for responding!
