As most of us are using CPF to finance our HDB purchase, the limitations on CPF usage may restrict our ability to buy an older HDB with less than 60 years remaining on the lease.
You may use the full CPF amount if the remaining lease can cover the youngest buyer until the age of 95 and a prorated amount if the remaining lease does not.
For example, if you are 35 years old and the flat you wish to purchase is built in 1977, your CPF usage is pro-rated, since the remaining lease (56 years) will only cover the buyer until the age of 91 years.