upgrade还是二手组屋的话不需要refund，直接算5%ABSD remission is granted in the following scenarios : - (i) For purchase of HDB flat/new EC by a household which comprises SC(s) and SPR(s) co-owners (ii) For purchase of HDB flat/new EC in cases where HDB grants the household a 6-month or such other period as may be stipulated by HDB to dispose of its existing property(ies) (iii) A lower ABSD rate of 5% (instead of 10%) will apply for purchase of HDB flat by SPR household where HDB grants the SPR a 6-month or such other period as may be stipulated by HDB to dispose of the existing property(ies) Remission for such purchases will be granted automatically upon approval of purchase by HDB. No separate application to IRAS or HDB is required. 来自： http://www.iras.gov.sg/irasHome/page04.aspx?id=12822