I have calculated my estimated taxes for 2021, however my income changed as of May significantly. Based upon my calculations for the year when I look at paying 90% of what is owed I do not owe any estimated taxes. At 100%, I do. If I choose to pay @ 100% but the first payment is past. How do I calculate the individual payments since there will only be 3 and, if my income continues to vary through self-employment, how do I pay estimated taxes in that instance?
