Retired couple with AGI over $150,000 and consistent each year by year end; but, not evenly received, due to Roth IRA conversions at different times of the year. We have no withholding on any income, so quarterly payments each year. Each year turbotax calculates quarterly payments based on 110% of previous years total tax. Each year there is a large excess eligible for refund or to be applied to current year's tax.
Rather than go thru overpay/refund each year, is it possible to make the first three quarterly payments based on the 110% figure and in January modify 4th quarter to equate to 100% of actual tax year tax and not incur any penalty or deal with form 2210? By that time, AGI & total tax could be figured close to 100%, but certainly more than 90%.
