51 Pa. Code § 21.22
This section cited in 51 Pa. Code § 25.4 (relating to appeal of determination); 51 Pa. Code §43.2 (relating to Commission proceedings under section 1307 of the act); 51 Pa. Code §43.5 (relating to investigative process for late or deficient filings); 51 Pa. Code § 63.2 (relating to Commission proceedings regarding prohibited activities under section 13A07 of the act); and 51 Pa. Code § 63.5 (relating to investigative process for late or deficient filings).