September 2023
5 September
- Employer deductions payment due for 16 to 31 August for large employers
20 September
- Employer deductions payment due for August for small to medium employers
- Employer deductions payment due for 1-15 September for large employers
25 September
- South Canterbury Anniversary Day
28 September
- GST return and payment due for taxable period ending 31 August
- AIM monthly due date
30 September
- Overseas-based student loan repayment due