Pubdate: Fri, 5 Sep 1997 By Geert De Clercq BRUSSELS, Sept 5 (Reuter) Moonlighting, the drugs trade and prostitution are set to boost Belgian gross domestic product (GDP) from 199798. In compliance with a European Union directive, Belgium's National Accounts Institute (NAS) will include estimates of proceeds from the large underground economy in GDP data from 1997, a central bank official told Reuters on Friday. For the 1998 GDP data, the NAS will also include estimates of revenue from illegal activities. ``That means casinos, drugs and prostitution,'' the official said. In theory, even money paid by a gangster to a hitman should boost the benchmark of economic growth. How to measure that, is another question. ``We are looking for a method,'' said the official. He added that private studies about the country's black economy had estimated its size at between three to 25 percent of official GDP. Friedrich Schneider, a professor at Linz university, Austria, estimated in a recent study the black economies in many EU states exceeded 15 percent of official GDP and even 20 percent in Belgium. In Belgium, where marginal tax rates are as high as 55 percent, tax avoidance is a national obsession. In sectors such as domestic help and home repairs, there is more unregistered labour than official labour, while in sectors such as restaurants and retail, where cash payments are predominant, a large part of turnover is realised outside the official circuit. The widening of the GDP measure to include all this could have a major impact on Belgium's state deficit to GDP ratio, the indicator most closely monitored by financial markets. The central bank estimates 1997 nominal GDP at 8,570 billion Belgian francs and the 1997 budget deficit at 240 billion francs, for a deficit/GDP ratio of 2.8 percent. If the inclusion of underground activities were to boost 1997 GDP by 10 percent to 9,427 billion francs, the deficit/GDP ratio would drop to 2.5 percent. A 20 percent boost to GDP would reduce the ratio to 2.3 percent. The central bank official said the GDP revision would not be used to flatter the country's ratios ahead of the European Union's review early next year of which member states are fit to join the single currency in 1999. ``The revision of 1997 GDP will not be released until September 1998, when the data must be reported to (European statistics agency) Eurostat. By then the single currency members will have been chosen,'' the official said. Several EU states have integrated estimates of their underground economies into official GDP data in recent years, including Italy, Greece, Portugal, Luxembourg and Ireland. The revisions ranged from five to 20 percent of GDP. The European Commission wants a better estimate of EU countries' real wealth to insure EU budget contributions, which are calculated partly on the basis of GDP, are fair.