Is the total tax paid through withholding plus excess social security
tax withheld at least 90% of the total tax? For example if you owe
100k and paid 90k through withholding and excess social security tax,
there is no penalty.
How much tax did you pay last year and how much tax did you pay this
year through withholding and excess social security tax, and are you a
farmer or fisherman? If you paid 100k last year, are not a farmer, and
if this year you have paid 110k through your W-2 and other 1099 forms,
then there is no penalty either.
Do you also make estimated payments, and if so did you make equal
estimated payments? That also complicates things.
Worst case, you'll have to file long form 2210 to reduce the penalty --
which will certainly reduce your income if most of your income came in
the last quarter.