More than 500 public rental tenants bought their first homes last year, according to fresh figures from the Housing Board.

Although this is fewer than the 750 in 2014, the latest number does not include tenants who applied for a new flat during November's bumper launch featuring 12,411 flats, about half of last year's supply. Figures are not yet available.

Since 2011, more than 3,000 tenants have bought their first homes in Build-to-Order or Sale of Balance Flats exercises. This is up from about 2,500 a year ago. There is "a steady stream of about 600 households per year", said the HDB.

Under the public rental scheme, eligible needy families with a household income of up to $1,500 can rent flats at highly subsidised rates.

Rents start at $26 for a one-room flat and $44 for a two-room flat. Each tenancy is for two years, after which the HDB assesses renewal.

"Tenants who are financially stable will be encouraged to consider buying a flat," said the HDB.

Grants to help families buy their first flat have also risen. From the November 2015 launch onwards, eligible first-timers can get up to $80,000 in housing grants. This comprises an Additional CPF Housing Grant of up to $40,000, and the Special CPF Housing Grant (SHG) of up to $40,000. The maximum SHG amount was $20,000 before.

Of the tenants who have bought their first flat since 2011, 84 per cent did so with the help of either or both grants. And 12 per cent got the maximum grant amount, which was $60,000 at the time. Some tenants may not have qualified for the grants due to eligibility criteria such as needing to be employed continuously for 12 months before application.

First-timer public rental tenants also get priority to buy new flats, with 10 per cent of two-room flexi and three-room supply set aside under the Tenants' Priority Scheme.

Since 2011, about 19 per cent of tenants who bought a flat did so under this priority scheme.

Overall, 73 per cent bought a three-room or smaller flat, "with the majority buying a three-room flat", said the HDB.

But tenants who have owned a public flat before will get more help with the upcoming Fresh Start Housing Scheme, to help second-timer families with young children own a flat again. The Government is studying offering eligible families a new housing grant to buy a two-room flexi flat with a shorter lease, but with stricter resale conditions.