You need to register for GST with IRD (Inland Revenue Department) if you carry out a taxable activity and your annual turnover (gross sales) are more than $60,000, or if GST is included in your selling prices.
GST Return frequency has 3 options i.e. 1 monthly, 2 monthly , and 6 monthly. For most small business we recommend the standard option of a 2 monthly Return filing period, as this works best for the business Cash Flow. Many astute business owners say doing this ensures that their small business accounts are up to date, and it gives them (the owners) an up to date picture of their financial performance.
GST Returns must be filed by the required time, even if you have no income or expenses for that Return period.
Using a good accounting package such as Xero, can make completing your GST Return a lot easier and quicker.