$64.$ Anna does not make quarterly estimated tax payments

even though she has substantial amounts of income that are not subject to withholding.

In the previous year, Anna$$s tax liability was $$18,000$ and her AGI was $ $135,000.$ In the

current year, Anna$$s actual tax liability is $$30,000,$ and $$18,200$ was withheld from her

salary.

a$.$ Is Anna subject to the underpayment penalty? Why?

b$.$ If Anna$$s withholdings were only $$15,000,$ would she be subject to the underpayment

penalty? Why?

c$.$ If Anna is subject to an underpayment penalty, can she deduct this amount as interest?

Explain