well, there you go.. the ST article on the so-called loophole, though HDB refuses to admit that it was a tactic used by 6000 HDB dwellers every year, since the ABSD rule came into effect in 2012.
lets low ball this figure and assume only 1000 dwellers out of the 6000 every year, bought a modest $1m private property. A quick calculation will show that the $210m (7% ABSD) of ADSB lacking from the tax coffers. The paper-pushing president scholar sitting in the housing ministry should be promoted for discovering this loophole and thus saving millions for the government.
I blogged a short post on this a few weeks back. Decoupling loophole; plugged.