Because of an error with my W2, I think I may have underpaid medicare and social security taxes. Basically my employer did not include part of my salary in my W2 so the withholdings were off. They ultimately corrected the W2 with a W2C and paid their part of the missing social security and medicare withholds. I think just my contribution may be underpaid.

Does anyone know what happens in this scenario? Is there a form I need to file? How do I make these payments? Anything else I should know?