Under the Enlistment Act, all male Singapore citizens and Permanent Residents are liable for National Service (NS). Upon reaching the age of 16.5years, all male Singapore citizens and Permanent Residents (including those whose Singapore citizenship is a second citizenship), have to register for NS.

Male children who are granted PR status under their parents' sponsorship are liable for NS under the Enlistment Act. They are required to register for NS upon reaching 16 .5 years old and will be scheduled for enlistment at the earliest opportunity upon reaching 18 years old.