NeezaNizam discusses the possibility of upgrading an HDB without selling it, highlighting the conditions and terms involved. He explains that HDB owners must wait five years from the minimum occupational period (MOP) before considering a second property. The total debt servicing ratio (TDSR) and additional buyer stamp duty (ABSD) are crucial factors. 

For a second property, the ABSD is 20% of the property value, which can be refunded if the HDB is sold within six months. Nizam shares that his clients managed to secure a 75% loan for a new property without affecting their TDSR but faced a hefty ABSD. He advises that this strategy is suitable for those with strong cash flow and emphasizes the importance of timing and financial planning.