If after a taxpayer files his final tax return, facts are discovered or events transpire which would increase the taxable income or tax of the taxpayer or both, it shall be the duty of the taxpayer to file an amended return with the Personal Income Tax Bureau within 30 days from the date of the determination of such increase. The amended return shall indicate the changes made, and a statement shall be attached setting forth what facts or events gave rise to the need for such amended return. If the amended return indicates additional taxes are owed, a check for such additional amount shall be attached to the amended return. Examples of events causing an increase in income or tax liability include, but are not limited to, the following:
61 Pa. Code § 117.9a