According to the official SDL SSG FAQ
SDL is not payable for the following employees:
An employee who is a domestic servant, chauffeur or gardener wholly and exclusively employed by an individual otherwise than in connection with that individual’s trade, business, profession or vocation.
An employee who does not render any services in Singapore in relation to a month. This excludes employee who is on leave for that month that is arising from his or her employment in Singapore.
For both the above categories, employers are required to login to the SDL system to submit declaration on non-liability of SDL to SSG for these employees via the E-Declaration module with the details of such employees (e.g. employees’ details, duration in which the employees are working overseas, etc.). Please refer Section 9 – Declaration on Non-liability of SDL for more details on the procedure and supporting documents. For system instructions, please refer to the SDL System User Guide on the E-Declaration module (Section 3.12 E-Declaration).
An employee who is the subject of exemption under the Skills Development Levy (Exemption) Order 2014 made under the Skills Development Levy Act (Chapter 306). Details as follow:
A matriculated or registered student of any of the following institutions who is employed for the training approved by the institution in question:
Institute of Technical Education
Nanyang Technological University
National University of Singapore
Ngee Ann Polytechnic
Singapore Institute of Technology
Singapore Management University
Singapore University of Social Sciences
Singapore University of Technology and Design
A matriculated or registered student of any overseas tertiary education institution who is required by the institution to undergo training in Singapore for a period of not more than 6 months. The exemption of SDL is subject to the condition that the employer of the student submits to the SSG a letter issued by the overseas tertiary education institution which confirms that:
The student is a matriculated or registered student of the institution;
The student is required by the institution to undergo training in Singapore.
A registered student (other than a student who has completed his “A” level examinations) of any school registered under the Education Act (Cap. 87) and who is employed during the gazetted school holidays.
Students of Government schools, excluding tertiary institutions, working during their scheduled school holidays.
'N' & 'O' level Government school students working during the scheduled school holidays.
‘A’ level students working during scheduled school holidays before their "A" level examinations.