Hi David, may I know on average how much downpayment for mortgage do I need to pay for a normal HDB BTO or HDB resale flat?

There is no real difference in the requirements between the downpayment for a BTO or resale flat.

The downpayment amount depends on whether you're taking a HDB loan (HLE) or a bank loan.

If you are taking a HDB loan (HLE) the loan can cover a maximum of 90% of the flat costs. However, HDB will require you wipe out your CPF OA first (except for $20k which can be retained for each owner), including paying for the downpayment of 10% of the purchase price.

If you take bank loan, you have the option of not using CPF at all for the downpayment. However, the downpayment is at least 25% of the purchase price, and at least 5% must be paid in cash.