A certified true copy of the Sales and Purchase document is required if the address of a yet-to-be completed private property is used for registration. The date of commitment by the developer in the Temporary Occupation Permit (T.O.P.) has to be within two years of the child’s entry into Primary One. In the case of a yet-to-be completed HDB flat, the Customer Copy or Specimen Copy of the Agreement for Lease is required. The Delivery Possession Date of the flat has to be within two years of the child’s entry into Primary One.
Parents must move into the new property within two years of the child’s entry into Primary One.
- See more at: https://www.moe.gov.sg/admissions/primary-one-registration/required-documents-for-primary-one-registration-exercise#proof-of-purchase
所以应该是2年。
