Dear sir/madam, I am assuming that you are intending to upgrade therefore doing your fair share of homework on this aspect. All SPR or citizens will only be allowed to own 1 unit of HDB therefore in cases of upgrading, as long as your finances allow you to make your purchase of the bigger unit first without selling the existing one, you can proceed to do so, and only to sell your existing unit after you have moved into the newly purchased unit. The window period allowed for you to sell your existing HDB will be 6 months from taking possession of your purchased HDB. I am not sure if I have addressed your concerns but do get back to me if you require any further assistance. Thanks. Visit and Like my facebook page at https://www.facebook.com/propertyblogshop Regards, Geryl LIM Real Estate Director Masters Of Real Estate (L3010548F) CEA Reg R014783H Mobile: +65-81577565/+65-92787772 Email: email@example.com M.O.R.E Landed Dynamic Alliance Home of *7772 Hotline Check out our latest Landed Dynamic Alliance 7772 mobile application on iOS or Android @ "Landed 7772" in Mobile Apps Store or Play Store now! Our next exhibition is on 2nd and 3rd August 2014. If you have missed out successful exhibition on 10th and 11th May, do not miss this opportunity again. Register your interest to attend this showcase event now!