Belgrade — The typical Yugoslav had to tighten the family's belt by 7 percent last year, and by almost as much in 1981. If Yugoslavs are not rebelling - like the Poles - it is because many can draw on savings made in the previous decade of ever-increasing income.
This drop in Yugoslavia's standard of living has come about through an inflation that in 1980 was the highest in Europe - 30 percent officially and 40 percent for the man in the street. In the opening months of this year inflation hit almost 50 percent and has now ''calmed down'' to under 40 percent. Especially at a time of slowed economic growth this is a dramatic jump from the bearable 18 percent annual inflation of the high-growth 1970s.
The roaring inflation has led to several distortions. The first is the 7 percent gap in the family purse between normal wage increases and inflation. The average Serbian now has to spend almost half of his budget for food. And he probably has had to postpone buying a car or color TV because credit was frozen on such items last year in an anti-inflation measure. All now require 100 percent cash.
This relative austerity, if prolonged, could lead to political unrest. It has not yet done so, however, and none of various economists, journalists, and foreign diplomats asked about the issue saw any immediate risk of disturbances. Strikes, for example, have remained localized so far and have stayed within the normal range of collective bargaining without spreading or becoming politicized.
Nonetheless, Yugoslav planners have no desire to invite trouble and are keeping a wary eye on personal consumption. The most optimistic official hoped that the standard of living could be kept stable in 1981. Most others expected personal consumption to fall for a second consecutive year, however, and projected no real growth until the end of the 1981-85 five-year plan.
There are even more serious consequences to inflation than belt tightening. One result is a drop in competitiveness of Yugoslav exports - until last year's 30 percent devaluation of the dinar and now again as the effects of devaluation begin to wear off.
A second consequence is a happy-go-lucky attitude toward investment. ''Maybe a third of (recent) investment was probably not to the point,'' notes Vinko Mir, assistant secretary for foreign trade.
This waste was not all the fault of inflation. But inflation was a powerful factor. With 30 or 40 percent inflation and an 8 to 9 percent interest rate - in one of the enduring communist shibboleths, interest is kept artificially low - it makes eminent sense for enterprises to borrow as much as possible and pay back loans in cheapened currency a year or two later.
Even after this year's tightened reins, half of the country's investment was still being financed by bank credits, the Belgrade newspaper Borba complained last June.
In an economic system with greater reliance on the market, the threat of bankruptcy as well as soaring interest rates might be expected to cool off investment fever. But in Yugoslavia, Western observers point out, industries are rarely allowed to fail. As a result, economic decisions are separated from their consequences - and this strengthens the impulse to investment provided by inflation.
In this environment Yugoslavia has many reasons to wish to tame its inflation: to keep social peace, to boost slumping exports to the West, and to rationalize investment in accord with real economic and social costs.
The inflationary habit is hard to kick, however; Yugoslavia has been only partly successful.
Until January 1981, administrative controls were exercised over two-thirds of prices, primarily at republic or municipal level, with the remaining third left to free-market play. With the 1981 reform, the intent was to make market forces the main determinant of prices. Each enterprise would set its prices through agreement with customers, with review by the (usually local) government for social equity.
There was, however, an interregnum before the new system actually took hold. Enterprises rushed to raise prices as soon as controls were lifted, and prices soared to the country's highest inflation since World War II. The Federal Executive Council concluded that things were out of hand and in June introduced direct price controls for virtually all products for six months.
Newly formed ''self-managing committees of interest for prices'' were made responsible for prices - but these decentralized committees are bound to federal guidelines of no more than 7 percent increase in industrial and retail prices, and 5 percent in services, so long as the cost of living doesn't rise more than 7.5 percent between June and the end of the year.
More optimistic economists like assistant Federal Secretary of Finance Gavra Popovic argue that Yugoslavia made it ''over the hump'' with June's one-month inflation of only 1.6 percent - and that the country can meet its 1981 inflation target of 32 percent. More cautious ones, like Stojan Stamenkovic, assistant secretary for the market and economic affairs, say only that Yugoslavia can probably ''manage below 40 percent.''
Would this be enough of a declaration to let the current price controls expire at the end of the year? Mr. Stamenkovic expects that by Dec. 31 only some 20 to 30 percent of prices, including energy and utilities, ''will still remain under some control''; 40 to 50 percent will be decided by enterprises and ''registered'' (apparently with discretionary administrative review); and the rest will be decided fully by supply and demand.
Western observers, however, doubt that such a mass liberalization of prices would work any better in January 1982 than it did in January 1981.
Apart from administrative control, the major government restraint on inflation is its monetary policy. For the past three years, explains Dimitrije Dimitrijevic, National Bank of Yugoslavia research manager, Yugoslavia has kept the money-supply increase below the gross domestic product (GDP) increase. Over the past two years it was about 10 percent lower; this year it is being held to a 22 percent increase despite an expected nominal GDP increase of 35-40 percent.