On New year's Eve, office workers here traditionally throw out the old year by flinging files out the windows, creating paper blizzards throughout the financial district. But the parties are over, and Brazil's bankers and economists are now waking up to a hangover nastier than usual -- their economy has started the New Year as the most troubled in Latin America and in the western world.

Inflation, at a record 113 percent,is the second highest in the world, and the foreign debt, at $56 billion and rising, is the highest in the world.

Gigantic Brazil buys 85 percent of its oil overseas, and economists blame this costly burden for the high inflation and debt, which both started climbing steadily after the 1974 oil hikes. Indeed, of Latin America's five largest economies, Brazil is the only nation to import more than 20 percent of its petroleum.

Each $1 price rise for a barrel costs the country $250 million, In 1979, Brazil was paying $14.54 for a barrel. By last month the price had doubled to $32 -- now eating up half of the country's export earnings.

Further clouding the new year, Saudi Arabian oil minister Sheikh Ahmed Zaki Yamani talked last month of another doubling, to $60 a barrel. At present consumption levels, this price would reduce Brazil's already frugal list of imports to one item -- petroleum.

This gloomy arithmetic is causing wary foreign bankers to concede loans for shorter terms and at higher rates than usual to Brazil, the go-go growth country so much in vogue 10 years ago. Instead, financiers and industrialists from Europe, Japan and the United States now are flocking to oil-rich Mexico and Venezuela.

To document the problem, a weekly financial newsletter from London, the Agefi Letter, last month surveyed 383 bankers from 34 countries about Brazil. Sixty percent said their banks had reached their lending limits for the country.

Only 12 percent said they were willing to make new loans to Brazil.

Asked to comment on this report, Brazil's formerly ebullient planning minister Antonio Delfim Netto only grambled, "just because it's printed in English, everyone gets all afluttter." However, adding to Delfim's headaches, two-thirds of Brazil's foreign debt will come due by 1985, and the largest lump of repayments, $8 billion, is due this year.

These pressures may force Brazil to resort to the International Monetary Fund for an estimated $8 billion in loans spread over three years. An IMF loan would probably be tied to a mandatory austerity program -- a condition attacked by local nationalists as foreign meddling and hailed by international bankers as a certified stamp of approval for the nation's economic policies.

Skillfully tiptoeing between both camps, Delfim voluntarily unveiled new policies that Michael J. Gibbs, local representative of the Bank of America, later pronounced as "exactly the same as the IMF would demand of the Brazilian government."

Aiming to reduce inflation, but to also expand exports to wipe out this year's $3 billion trade deficit, Delfim announced a two-tiered policy of lavish subsidies for export industries but tight money for domestic-oriented companies. His goals for 1981 are to increase exports by 25 percent to $25 billion, while holding imports to a 4 percent rise to $24 billion.

If Delfim sticks to his guns, the nation will be shocked into a recession -- Brazilian-style. Growth rates are expected to drop from last year's inflationary 8.5 percent to 4 percent -- Brazil's lowest in 15 years.

Last year Delfim predicted inflation would fall to 50 percent. This year Treasury Minister Ernane Salveas is forecasting a drop to 70 percent -- a prediction many now-skeptical Brazilians are taking as seriously as the cotton snow on their tropical Christmas trees.

For the ruling military, 1981 is the year for quick, effective economic cures. In late 1982, for the first time since the generals seized power in 1964, their economic policies are to come to a serious electoral test. Brazilians are to vote for most mayors, most congressmen and all governors. In 1985 this pool of about 1,000 elected officials is to act as an electoral college and choose Brazil's next president.

Already, poor economic performance is blamed for the government party's rapidly dwindling majority in the powerless chamber of deputies, where government members are defecting to the five opposition parties.Indeed, one jittery government deputy recently accused Delfim and Salveas of being "excellent precinct captains for the opposition." Delfim, who came into his job 18 months ago with presidential ambitions, is now said to be fighting hard not to get fired.

In the economic arena, the government has speeded up the fight against oil imports by raising the price of gasoline to $3.60 a gallon-- the fourth highest price in the world and now more expensive that the sugar cane rum popular here. In the wake of this price hike, the nation's five largest automakers reported a slump in sales. Volkswagen, the leading manufacturer here has 50,000 unsold cars sitting on lots, and last month the company announced its first loss in 27 years of operation in Brazil.

The automakers are fighting back with the government's other major weapon against imported oil: an ambitious program to run the nation's fleet of 6 million cars on sugar-based alcohol. Responding to sharply increased demand, automakers have vowed to double last year's production of alcohol cars to 600,000 in 1981. By 1982, they say they will make gasoline-powered cars only for export or for special order. Already one third of Brazil's service stations pump alcohol as well as gasoline.

Looking at the rest of Latin America, Chile is the only other major economy dependent on imported oil -- 81 percent in 1979. But hefty increases in the price of copper, the country's primary export, have allowed Chile to keep up with the oil payments and even to show a trade surplus this year.

An economic basket case when the military seized power in a bloody coup in 1973, Chile has since been a laboratory for the theories of Chicago-trained economists. They lowered import tariffs, ended subsidies, abolished foreign exchange controls and returned much of the nationalized economy to private hands.

High employment ensued, but is now slowly receding, and the predicted national growth rate of 6 percent for 1980 matches the continental average. Inflation, after hitting a highwater mark of 700 percent is expected this year to be around 30 percent, also near the average for Latin America.

While Chile is coming out of a shock treatment of free enterprise remedies, Argentina, under a Harvard-trained economy minister, is just beginning the process: Six banks have folded this year; the largest economic conglomerate, Sasetru, has filed for bankruptcy; and an artificially over-valued peso has destroyed a healthy trade surplus and made Buenos Aires the world's most expensive city.

A recent cost of living survey pegged New York at 100 percent, Rio at 81 percent and Buenos Aires at 161 percent. On the bright side, Argentine inflation is at its lowest point in five years.

Although figures for 1980 are not yet in, the landlocked countries of Bolivia and Paraguay are believed to have had a good year. Paraguay is currently riding a small boom stemming from $250 million generated annually by the construction of the world's largest dam, Itaipu, on the Brazilian border.Cocaine has allegedly replaced tin as Bolivia's top export, and the country is said to be awash with foreign exchange.

The twin northern countries of Columbia and Venezuela have reported growth and inflation rates pacing Latin American averages and oil-soaked Venezuela still leads the continent in per capita income.

All but two of Latin America's 12 republics border on Brazil, the continent's leader in land-mass population and gross national product. Independent economists believe that if Brazil can overcome the immediate oil obstacle, the country has the best long-term prospects of the area.

Itaipu, which is to come on stream in 1985, will only scratch the surface of Brazil's enormous hydroelectric potential. In the eastern Amazon, the government is embarking on a $34 million project to mine the Carajas, range which holds the world's largest deposit of iron ore as well as massive quantities of copper, manganese, tin, nickel and bauxite. A government report released last month says Brazil has the world's largest supply of gold.

Indeed, when a Brazilian economist was recently asked to comment on reports that Brazil has the most troubled economy in the western world, he snapped: "jealousy."