SINGAPORE'S goods and services tax (GST) is more than one year away, but already employers are worrying about the effect on wages, shopkeepers are concerned about the effect on tourists, and Singaporeans generally are anxious about the effect on their wallets. To be implemented on April 1, 1994, the GST of three per cent will be accompanied by cuts in corporate and personal income tax. The Government hopes the GST would make Singapore more competitive and more attractive to foreign businesses. No hint has been given of how much relief Singaporeans can expect, except to say taxes will be reduced ''significantly''. Singapore has a corporate tax rate of 30 per cent and a top income tax rate of 33 per cent. Companies with an annual turnover of less than S$1 million (about HK$4.7 million) will not have to levy the GST, an exemption extending to 79 per cent of businesses. But the effect of the GST on these smaller businesses, through their purchases from suppliers, can be expected to feed through to their customers in the form of higher prices. The rental and sale of residential land and buildings will be exempted from GST. As a result of the planned reductions in corporate and personal income taxes and the implementation of other measures to offset the impact of the new tax on lower income earners, retired people and pensioners, the government expects to collect less revenue in the GST's first few years of operation. In the longer term, the changes should be revenue neutral as long as the GST rate is not increased. A White Paper said the government did not intend to change the GST rate for at least five years. It said income tax for most households would be reduced by more than the amount of GST they would have to pay. Many households would no longer have to pay income tax. In addition, the government would reduce a number of existing taxes on consumption items, such as entertainment duty and utility and telephone charges. Subsidies to the state education system and to the public health system would be increased to offset GST payable for education and health services. The White Paper said the GST would provide a stable source of revenue and enable the government to meet any future shortfall in revenue due to higher expenditure or lower direct taxes. Singapore's tax system would remain progressive even with a GST, it said, but added that ''progressive'' and ''regressive'' were ''epithets more relevant to the debate in the 1950s and 1960s when people believed governments could increase well-being by redistributing wealth and levelling down the more successful in society through taxation''. ''Those policies have failed all over the world,'' the White Paper said. ''The true test of a government policy is not how heavily it penalises the more successful but whether it makes everyone, rich and poor, better off by rewarding enterprise, by encouraging all to strive harder, by promoting savings and investments and thus economic growth. In these respects the GST will improve our tax structure.'' Not everyone agrees. Retailers and the tourism industry have expressed concern over the government's decision not to implement a system of tourist refunds, although the White Paper said it would consider doing this if tourist shopping was ''badly affected''. Calling on the government to implement a refund system, the Singapore Retailers' Association (SRA) said Singapore already had an expensive image as a tourist destination. With the GST, tourist-dependent businesses, especially retailers, would be badly hit. The SRA president, Mr B. L. Teh, said refunding the GST to tourists would send them a clear message that the tax was a domestic affair. Larger retailers complained that the GST would drive businesses away from major shopping areas, such as Orchard Road, to smaller, neighbourhood stores, which were exempt from levying the tax, although prices there might not be significantly different. At a press conference announcing the government's plans, the Finance Minister, Mr Richard Hu, said the GST should not be taken into account when considering wage rises. ''It's no more than the average rate of inflation and it is one-off, don't forget, and not inflationary,'' he said. Employer groups said there was widespread concern that the GST would put upward pressure on wages by fanning inflation. Already expecting a growing demand for wage increases over the next three years in Singapore's tight labour market, employers believe workers will now use the GST to press their case. Although Mr Hu said prices should rise by no more than three per cent and the government would monitor price changes to guard against profiteering, consumers' representatives said they feared some shopkeepers and businesses would try to take advantage ofignorance about the GST. The Consumers Association of Singapore (CASE) described the new tax as an ''unquestionable burden on the pockets of consumers'' and said profiteering was a ''major anxiety''. It called for additional assistance from the government to help it step up its efforts to provide information on prices, conduct price surveys and identify profiteers and traders with bad practices.