Answer:
When a taxpayer has an underpayment of estimated tax or fall behind on his/her tax prepayment, then he/she is required to pay a penalty on Form 2210. This penalty is called underpayment penalty.
According to the tax laws, Mr. P and Ms. S can avoid an underpayment penalty if their withholding's and estimated tax payments equal or exceed one of the following two safe harbors:
- 90 percent of current tax liability ($200,000 x 90% = $180,000)
- 110 percent of previous year tax liability (110% x $170,000 = $187,000)
From the above calculation, it is clear that Mr. P and Ms. S's withholding's ($175,000) do not equal or exceed the amount of two safe harbors. So, they need to increase their withholding's or make estimated payments to avoid underpayment penalty.
If Mr. P and Ms. S increase their withholding's by $5,000 or make estimated payments of $1,250
per quarter ($5000/4), they can avoid the underpayment penalty.
Mr. Paula and Simon average gross income is greater than $150,000, so 110% is taken.