Liability for liquidation: liquidator must notify commissioner and directors may be jointly liable for unpaid tax absent gross neglect. When a company is being wound up the liquidator must notify the Commissioner within thirty days; the Commissioner shall, after inquiry, notify within three months an amount sufficient to cover tax, interest or penalty due or likely to become payable. If a private company's tax, interest or penalty cannot be recovered after winding up, every person who served as a director during the period of liability is jointly and severally liable unless he proves to the Commissioner that non-recovery was not due to gross neglect, misfeasance or breach of duty.