You generally cease being a tax resident when you have left the country for more than 325 days and no longer have a permanent place of abode. If you remain a NZ tax resident whilst working overseas, make sure you keep your payslips or summary of earnings as the overseas income, as well as the tax already paid on it, will need to be included in your NZ return. Tip: To find out whether you will remain as a tax resident complete an IR886 form.