While the penalty is small you might want to look at your withholdings at each Quarterly testing date. You can compute the penalty by claiming the actual amount of withholding each quarter and if it is large enough it might reduce the penalty - maybe even eliminate it. Pull up Form 2210. The IRS computes the penalty using the assumption the taxes were withheld equally all year. However if you had a bonus or more income in the early part of the year - your withholding might be greater in Q1, Q2 or even up to Q3 and eliminate the penalty in those earlier quarters.
