You may apply for HDB's Public Rental Scheme if you are a Singapore Citizen and have a child under your legal custody (care and control).
You must be at least 21 years old at the time of application and your total household gross income should not exceed $1,500 per month. If your monthly household income is more than $1,500, you can still submit an application. HDB will review your application, taking into consideration whether you have other housing options.
We wish you all the best in your application.
Hope this answers your question.