The government launched a series of measures on September 29 to cool down the real estate market, including the requirement that private homeowners must wait 15 months after selling their homes before they can buy non-subsidized HDB flats, in the hope of easing the demand for HDB flats for resale and stabilizing prices.

The new measure is intended to "stabilize the HDB market", but it has led to voices saying that "people should not be allowed to own both HDB flats and private homes, and that HDB flats should not be used as a money-making tool".

Some people rent out their HDB flats and use the rental income to pay off the loan for their private homes. Others live in semi-detached houses and own several overseas properties, and have been renting out their HDB flats for decades to earn rent.

Currently, HDB upgraders and private home downgraders receive different treatment.

Since August 2010, the government has required private homeowners to sell their private homes within six months if they purchase a HDB flat, but still allows HDB flat owners to keep their HDB flats after upgrading to private homes.

Now the new measures require private homeowners to sell their homes after a 15-month waiting period before they can buy a HDB flat.

Some analysts say that it has become a "norm" for HDB flat owners to rent out their flats after they have been upgraded to private flats, and now that mortgage rates are rising, homeowners will not give up this money-making tool.

In 1989, the government allowed people to keep their HDB flats after buying private homes, and in 2003, it further relaxed the regulations to allow HDB flat owners to rent out their entire flats. Since then, more people are believed to be doing so.

For larger families, there is nothing wrong with owning both HDB flats and private homes, but there are some people who run HDB flats as a business.

According to September estimates released by property website 99.co and Singapore Real Estate Syndicate (SRX), private home rents climbed for the 21st consecutive month, with overall private home rents rising 30.9 percent year-on-year.

The HDB rental market is also hot, with rents rising for the 27th consecutive month in September and overall rents up 24.7 percent over the year.

Singapore's public housing development is an enviable achievement, and its home ownership housing policy is world-renowned.

Over the years, the housing policy has been updated in line with the development of the city and the economy.

Every time a policy is adjusted or a new policy is introduced, it is impossible to be all things to all people, which always makes some people happy and some people sad. As a result, there are many comments on the fairness of the HDB system, and old issues become new ones.