Your services are considered international services, which are zero-rated (i.e. GST is charged at 0%), if they fall within the provisions under Section 21(3) of the GST Act.  Depending on the nature of your services, you may be required to determine your customer's belonging status (i.e. whether the customer is a local or an overseas entity) before your supply of services can be zero-rated.

Under certain zero-rating provision e.g. section 21(3) (j), (k) and (s), you need to determine the belonging status of your customer, that is whether your customer belongs to a country outside Singapore before you can zero-rate your services.

Q:	What if customer is an individual?
A:	Your customer will be treated as belonging in Singapore if his usual place of residence is in Singapore during the period of service. For GST purposes, an individual should have only one usual place of residence at any point in time. The “usual place or residence” means: 1. The individual stays in that country voluntarily and for a settled purpose (e.g. to pursue a course of study or employment); 2. The individual's stay in that country has some degree of continuity apart from temporary or occasional absence, and is part of the regular and habitual pattern of his life.
Q:	What if residential address as proxy?
A:	The Comptroller of GST may regard the residential address of an individual as his "usual place of residence". If your customer has a Singapore residential address, he will, for GST purposes, be regarded as belonging in Singapore.
Q:	What if more than one Residential Address?
A:	Where an individual stays overseas to study or work and he has more than one residential address, the Comptroller of GST may regard the individual as belonging overseas when all of the following conditions are satisfied: 1. He is absent from Singapore for a continuous period of at least one year. Any temporary return to Singapore for vacation or other reasonable purposes is acceptable; 2. He stays at a fixed place in the overseas country; 3. Where he is working overseas, his overseas assignment must not be related to his employment in Singapore. For example, an individual sent to work overseas by his local employer will not satisfy this condition and he will be treated as belonging in Singapore. If your customer meets all these conditions, he is treated as belonging overseas for the entire duration of his overseas stay.
Q:	What if customer is a Business?
A:	Your customer will be treated as belonging in Singapore when: 1. It has a business establishment or some fixed establishment in Singapore and nowhere else; 2. It is legally constituted in Singapore (e.g. company incorporated in Singapore) and has no business or fixed establishment in any other country; 3. It has establishments both in Singapore and outside of Singapore but services are most directly used or to be used at the establishment in Singapore.
Q:	What if business establishment?
A:	Your customer will be treated as having a business establishment in Singapore if: 1. his main seat of economic activity is in Singapore; 2. he carries on his business through a branch in Singapore; or 3. he carries on his business through an agency in Singapore. The main seat of economic activity refers to the place where the essential decisions concerning the general management of the company are made and where the functions of its central administration are carried out. It usually refers to the head office, headquarters or principal place of business.
Q:	What if fixed establishment?
A:	A fixed establishment is an establishment, other than the business establishment, that has both the technical and human resources necessary to provide or receive services on a permanent basis. Example: Company A is incorporated in Japan. It has no branch in Singapore. However, it has an office and staff in Singapore to help provide support services to its Singapore customers. This office and staff are considered a fixed establishment in Singapore.