I checked the W2 and all the numbers are correct in Turbotax totaling to $1,540 overpaid to Medicare withholding based on Medicare wages. I will check with Audit Defense on Monday to see if they can find out why the IRS disagrees with 8959 in Turbotax. I did e-file 3/9/22, but had to send a hardcopy to the IRS in August when they challenged the withholdings in April and lost my faxed response. The e-file copy and the hardcopy all match and the number on line 24 of 8959 is exactly what the IRS added to my total tax due in 2021.
