Why is retirement sum set at 55 but Basic Healthcare Sum set at 65?

The CPF system aims to help you set aside savings for retirement. The more you set aside in your CPF for retirement, the higher your monthly CPF payout which you can enjoy starting from your Payout Eligibility Age. 

Recognising that older CPF members may have short-term cash flow needs before they receive their retirement payouts, CPF members can make withdrawals from their CPF account from age 55 (you can find out more about withdrawal rules at age 55). Therefore, the retirement sum is set at age 55, to strike a balance between providing flexibility in withdrawals at age 55 and ensuring adequacy of monthly payouts in retirement.

The Basic Healthcare Sum (BHS) is different. It is the estimated savings you need in your MediSave Account for your basic, subsidised healthcare expenses in old age. It does not affect your monthly payouts nor the withdrawals you can make from your other CPF accounts at age 55 or after. As healthcare expenses are uncertain, the BHS is fixed from age 65 when many Singaporeans retire, to help you save enough for your healthcare expenses in old age.