Liability of company directors can extend to unpaid GST where recovery fails unless lack of gross neglect is shown. When a company is being wound up the liquidator must notify the Commissioner within thirty days; the Commissioner shall, after inquiry, within three months notify the liquidator of the amount sufficient to provide for any tax, interest or penalty payable by the company. If tax, interest or penalty in respect of a private company cannot be recovered, every person who was a director at any time during the relevant period is jointly and severally liable unless he proves to the Commissioner's satisfaction that non recovery is not due to gross neglect, misfeasance or breach of duty.