The Housing Authority lost an average of $1,882 on each of its public housing flats in 2002-03, according to calculations based on the agency's budget and the total number of public units. Secretary for Housing, Planning and Lands Michael Suen Ming-yeung said yesterday it would be impossible for the authority to keep up current levels of service if it was unable to collect rent of more than 10 per cent of tenants' median income, as required under a court ruling last week. After the ruling, two tenants filed for refunds with the Small Claims Tribunal. The authority fears it could spark a flood of rulings that could cost it $4.5 billion on top of a further $48.7 billion in expected lost revenue over the next decade. According to its budget, the Housing Authority ran up a deficit of $1.733 billion in the year ending in March. The figure includes rental and other income of $9.75 billion, expenditure of $10.96 billion and a one-time gain of $530 million. In April, an authority spokeswoman told the South China Morning Post that there were 65,500 public rental housing flats on Hong Kong island, 238,000 in Kowloon and 335,600 in the New Territories - a total of 639,100. On a per-flat basis, the authority earned $15,262 on average in 2002-03. But it spent an average $17,144 on each flat, including rent, rates, depreciation and maintenance. The Housing Authority is required to pay rates and maintain each public housing flat. Maintenance and improvement fees took up the biggest chunk of the authority's spending last year, accounting for $4,758 for each apartment on average, or 28 per cent of total spending. Depreciation and staff salaries also accounted for between 21 to 25 per cent each. The bottom line is the Housing Authority's $1.733 billion deficit translated into an average $1,882 subsidy for each apartment, a figure close to the authority's own estimate. An authority spokeswoman said yesterday it subsidised each flat to the tune of about $154 each month.