According to IRAS, you will have to file your first Income Tax Return upon closing your first set of accounts. Take note that there are some tax incentives available for start-up companies to take some weight off your shoulders. For instance, the Tax Exemption Scheme for New Start-Up Companies will give you a 75% exemption on the first S$100,000 of your chargeable income and subsequently a 50% exemption on the next S$100,000. To find out if you are eligible, your Chartered Accountant can advise you with up-to-date knowledge and financial expertise.