One of our last posts indicated that the IRS had issued a notice indicating they might not assess the late payment penalty for returns that are extended and paid after April 15, 2013 if the return included certain forms that were delayed by the new tax law.
However, when you read the fine print, it appears that you still need to accurately estimate your tax and pay in at least 90% of this extra tax to escape the penalty.
In addition, if you are farmer who delayed their filing until after March 1, 2013 to avoid paying your taxes until April 15, 2013, remember that the underpayment penalty will now kick in if you wait until after April 15 to pay. This now means that your interest rate will be the current 3% rate plus the underpayment rate of 3% plus if you are hit with the late payment penalty, that is another .5% per month or an annualized rate of 6%.
If you add all of these rates together, you now get a total annualized interest rate of 12% (again none of it is deductible). We would suggest paying your tax by April 15 unless you really are certain you can earn more than 12% after-tax on your funds.