USA W-2 etc: Health insurance premiums not coded as pre-tax

[ChereCK]

I have a new client with a handful of employees. One of them accepted the offer of health insurance coverage, and the former bookkeeper coded the premiums as post-tax for the employee. Now the former BK is fired and I'm hired and have to prepare W-2's. What is the easiest way to fix this? My guess: redo the paycheck tax calculations for the year in a spreadsheet to determine differences, file amended 941's, and manually adjust the W-2 in QB before printing.

If anyone has any input, agrees (for my peace of mind) or has a better way, I'd love to hear from you.

Many thanks.