Which of the following is a true statement? All business expenses are deducted for AGI. Student Loan interest is deducted for AGI. Rental expenses are deducted from AGI. Investment expenses are typically deducted for AGI. underpayment penalty can be assessed by the IRS when: The taxpayer has not paid in at least 120% of prior year's tax liabili The taxpayer has not paid in at least 90% of current year's tax li: e taxpayer has not paid in at least 100% of current year's t taxpayer has not paid in at least 90% of prior year's tay