As GST is a consumption tax and is borne by the end consumer, it is not treated as a cost to the company. Businesses only collect the tax on behalf of the Singapore tax authority, IRAS. As a GST registered company, you need to collect GST from your customers for the goods and services provided by you and then pay the collected sum of the tax to the tax authorities. The invoiced GST must be paid quarterly through the GST tax filing. You can only charge and collect GST once you have done your GST registration in Singapore .