DURING Sir Piers Jacobs' tenure as Financial Secretary, as his successor Mr Hamish Macleod can expect to be reminded by Legislative Councillors in the budget debate this week, ''broadening the tax base'' became an annual budget catchphrase. Too small a portion of the population paid too large a proportion of tax. It was argued that a sales tax or a wholesale tax, would compensate. Despite his best intentions, Sir Piers never found the right moment for the introduction of his much loved sales tax. Landed each March with an embarrassment of riches and always reluctant to increase government spending, he discovered it made little political sense, particularly as it was opposed by consumers and the tourist industry. Hongkong's buoyant economy made it seem over-prudent. Nor are the territory's low tax levels such a disincentive to investment and productivity. Mr Macleod has not only narrowed the tax base, but he has dropped duties on perfume and made other simplifications of the tax system. He is facing a small budget deficit next year and much larger deficits in the years to come. Mr Macleod is too canny to step in where Sir Piers feared to tread. Indirect taxation is in bad odour internationally at the moment. Australia's election was lost on a proposed general sales tax. Indirect taxes hurt most those who can least afford to pay. Their initial introduction is inflationary. In an economy unable to spend the taxes it already levies, Mr Macleod has rightly judged that there is no need to antagonise a populist legislature.