2.5 Income Ceiling
(a) Application to buy a 2-room flat (non-mature towns/estates) (If Offered)
The total gross income of
all persons listed in the Application Form must not exceed $2,000/- per month at the time of application.
(b) Application to buy a 2-room flat (mature towns/estates)/ 3-room (standard) flat (non-mature towns/estates) (If Offered)
The total gross income of
all persons listed in the Application Form must not exceed $5,000/- per month at the time of application.
(c) Application to buy a 3-room flat (mature towns/estates)/ 3-room (premium)/ 4-room/ 5-room flat (If Offered)
The total gross income of
all persons listed in the Application Form must not exceed $10,000/- per month at the time of application.
See above in bold.
HDB won't allow you to circumvent the rule like that because it would be making a mockery out of the whole income ceiling requirement.