If the bulk of your income came late in the year, you can file Schedule AI (Form 2210) to annualize income and reduce or eliminate the penalty for underpayment of taxes in the earlier quarters of the year. Otherwise, your income is treated as having been received uniformly throughout the year, requiring that your 90% of your tax liability be paid uniformly throughout the year (unless you qualify for one of the other safe harbors, which seems to not be the case).
