Additions imposed for failure to file or to pay estimated tax.

(b) Any individual making an underpayment shall pay, in addition to the tax, an amount at the rate of 9% per annum of the underpayment for the period of the underpayment. The period of the underpayment shall begin on the day after such payment was due and continue until such tax is actually paid but not beyond the 15th day of the fourth month following the close of the taxable year of the individual.

(c) No additions to the tax will be imposed if such installment is paid on or before the last date prescribed for payment, and the amount of such payment is one of the following:

(1) At least 80% (66 2/3% for an individual who expects to obtain at least 2/3 of his total estimated taxable income from farming for the year) of the amount due on the basis of the tax shown on the return for the taxable year.

(2) At least as much as would have been paid if based on the tax shown on the return of the prior year of the taxpayer.

(3) Based on a tax computed by using the income of the taxpayer for the prior year and the current tax rate.

(4) At least 90% of the tax due on the actual income earned in the months preceding the due date of the installment in question. Source The provisions of this § 19.23 amended December 29, 1978, 8 Pa.B. 3826. Immediately preceding text appears at serial page (36084).