Minors who obtained Singapore citizenship by descent or registration must take the Oath of Renunciation, Allegiance and Loyalty (ORAL) after turning 21 and before their 22nd birthday to retain their Singapore citizenship.
Failure to take the oath
If you do not take the ORAL within 12 months of turning 21, you will automatically lose your Singapore citizenship on your 22nd birthday. If this happens, there is no guarantee you will be able to continue studying, working or living in Singapore on any form of Student's Pass, Work Pass or Visit Pass, or as a permanent resident.