The number of standard-rate taxpayers has fallen sharply, government figures show.
Only 66,565 people, or five per cent of the total 1.33 million salary taxpayers, paid the top rate of 15 per cent in the 1998-99 financial year.
A total of 78,002 people were taxed at the top level in the previous year.
The figures came as Financial Secretary Donald Tsang Yam-kuen said on Monday a tax increase was 'inevitable' as the tax base had narrowed.
He said increases were necessary to cut the budget deficit. He did not specify which taxes would be affected, but floated the idea of a consumption tax.
Mr Tsang said he expected the deficit to be less than the estimated $36 billion for the current financial year because the economy was recovering faster than expected.