| You may be able avoid this penalty if you owe less than $1,000 in tax after subtracting their withholdings and credits, or if you paid at least 90% of the tax for the current year, or 100% of the tax shown on the return for the prior year, whichever is smaller.
Generally, these payments should be made in four equal amounts to avoid a penalty. The IRS has stated that if you made unequal payments because your income was received unevenly during the year, you may be able to avoid or lower the penalty by annualizing your income. Use Form 2210, Underpayment of Estimated Tax by Individuals, Estates, and Trusts, to see if you owe a penalty for underpaying your estimated tax.
There are some circumstances where the IRS has specifically mentioned that may waive the penalty if:
1) "The failure to make estimated payments was caused by a casualty, disaster, or other unusual circumstance and it would be inequitable to impose the penalty."
2) "You retired (after reaching age 62) or became disabled during the tax year for which estimated payments were required to be made or in the preceding tax year, and the underpayment was due to reasonable cause and not willful neglect." | 
