Household income remains the best measure for assessing who qualifies for government social assistance schemes, said Senior Minister of State for Finance Indranee Rajah.
It is fair, and helps ensure aid reaches those who need more assistance, she told MPs who asked if the current method of means testing could be more flexible or targeted.
Currently, many social assistance programmes - such as the Community Health Assist Scheme (Chas) and ComCare schemes - use gross total monthly household income or monthly household income per capita as a criterion for eligibility.
During the debate on the Finance Ministry's budget yesterday, Mr Murali Pillai (Bukit Batok) asked if the Government could consider family income as a metric instead, so that schemes could be targeted at families at the relevant income level.
He cited the example of an elderly person living with his "middle-income" family, who might not be eligible for Chas - which helps those with a monthly household per capita income of less than $1,800.
On the other hand, a separate elderly person living apart from his "richer" family would qualify.
Ms Indranee replied that family relationships are "complex and fluid", and cannot be fully captured by data analytics systems used to determine eligibility. She also pointed out that the Government is not privy to family dynamics.
Mr Edwin Tong (Marine Parade GRC) asked if the ministry could refine the current eligibility criteria, which also consider the annual value of a resident's home.
Some elderly residents living in private properties have no income and little savings, he noted, adding that a needy person living at a relative's private house or apartment on goodwill terms would also be ineligible for some social assistance schemes.
Ms Indranee said in response: "Our underlying principle is to provide support according to need, and those in private housing are generally better off than those in public housing."
Nominated MP Randolph Tan also questioned the efficacy of payouts such as GST Vouchers, which have broad coverage and might be "diffused in their impact".
Ms Indranee said Singapore has a "progressive social system where support is extended to all, but those with greater need received more".
She acknowledged, however, that no criterion for means testing is perfect, and each has trade-offs.
"To date, the household income remains the best available proxy for family support. But we will keep in mind good and practical ideas on how to improve on this," she said.