12 Pa. Code § 151.3
Under section 502(c)(3) of the act (53 P.S. § 6924.502(c)(3)), every taxpayer who receives other taxable income not subject to withholding under section 512(3) of the act (53 P.S. § 6924.512(3)) shall make and file with the resident tax officer a quarterly return on or before April 15 of the current year, July 15 of the current year, October 15 of the current year and January 15 of the succeeding year setting forth the aggregate amount of actual or estimated taxable income not subject to withholding attributable to the taxpayer during the 3-month periods ending March 31 of the current year, June 30 of the current year, September 30 of the current year and December 31 of the current year, respectively, and subject to income tax, together with the source, nature, anticipated frequency and location of the taxable income. Every taxpayer filing a return shall, at the time of filing the return, pay to the resident tax officer the amount of income tax due or estimated to be due. The tax officer may waive the requirement to file a quarterly return and payment of income tax when the taxable income is received on less than a quarterly frequency or is anticipated to be an aggregate amount of less than $12,000 annually.
12 Pa. Code § 151.3