If at any time during the continuance of public assistance any change occurs, including but not limited to, the possession of any property or the receipt of regular income by the recipient or by any person who is included within a recipient’s grant, that, in the circumstances upon which current eligibility or amount of assistance were determined, would materially affect such determination, it shall be the duty of such recipient to notify as defined by regulation the local department of such change, and the local board may either cancel the public assistance, or alter the amount thereof. Any recipient who knows or reasonably should know that such change in circumstances will materially affect his eligibility for assistance or the amount thereof and willfully fails to comply with the provisions of this section, is guilty of a violation of § 63.2-522.