Rita forgot to pay her Federal income tax on time. When she actually filed (without a valid extension), she reported a balance due. Compute Rita's failure to file penalty in each of the following cases. Explain your answers, as necessary.
a. One month late, $1,000 additional tax due
b. Four months late, $3000 additional tax due
c. Six months late, $4,000 additional tax due
d. Four months late due to fraud by Rita, $5,000 additional tax due