When you sell your property, you will need to refund the CPF principal amount you withdrew with the accrued interest (P+I). If you have pledged the property to meet your retirement sum, you will also need to refund the pledged amount on top of the P+I. The refunded amount will be used to top up your Retirement Account, up to your Full Retirement Sum. You can find out the amount to be refunded by checking your Home ownership dashboard.