Director liability for unpaid GST makes directors jointly and severally liable unless they prove absence of gross neglect. Directors of a private company are jointly and severally liable for tax, interest or penalty on supplies where recovery from the company is not possible, unless a director proves that non-recovery cannot be attributed to gross neglect, misfeasance or breach of duty. On conversion of the private company into a public company, that joint and several liability does not apply to persons who were directors during the private period if recovery was not made before conversion; personal penalties on directors remain applicable.