Can Reagan get US to tighten its belt another notch?

As the smoke of political battle clears, the economic landscape in the wake of President Reagan's tax and budget victories stands out more clearly. That landscape seems to promise some bumpy traveling ahead -- involving White House, Congress, and the American people -- even if all goes as Mr. Reagan plans.

He has set up two economic goals, which on the surface appear antithetical:

* His tax cut program, just approved by Congress, will reduce US Treasury revenues by at least $700 billion between now and fiscal 1986.

* At the same time the President foresees the federal budget drying up its red ink and emerging into surplus in fiscal 1984.

Given the prospect of shrinking tax revenues, the only apparent way to balance the budget is to cut government spending, again and again.

After weeks of often agonized debate, Congress is putting the finishing touches on $37 billion worth of budget cuts for fiscal 1982, which begins this Oct. 1.

These cuts will affect programs into the future and Reagan estimates that $ 140 billion will be saved over three years, measured against current spending levels.

This enormous sum -- including cutbacks in social and other programs now benefiting millions of Americans -- will not, by itself, be enough to balance the budget by 1984.

In fiscal 1983, according to the Office of Management and Budget (OMB), another $29.8 billion worth of cuts must be made. These will be followed by trims of $44.2 billion in 1984, $38.5 billion in 1985, and $42.7 billion in fiscal 1986.

These cuts have not yet been specified by the White House. Presumably, however, much will have to come from programs involving payments to individuals, especially if defense spending continues to rise.

Despite the President's pledge that current social security recipients have nothing to fear, the growth of social security benefits in the future may have to be scaled back.

Reform of the social security system promises to be the next major struggle within Congress itself and between lawmakers and the White House.

Another way to understand the budget problem is to use figures supplied by the White House, projecting government tax revenues under current law and under the Reagan tax cut program just passed by Congress.

In 1983, according to OMB, total receipts under current law would be $798.2 billion, but only $705.8 billion under the program about to become law. Equivalent figures for 1986 are $1,146.9 billion under current law and $923.3 billion under the new law.

Seen in this light, continuing cuts in government spending are needed to bring the huge federal budget into balance.

Reagan's economic program is based on the premise that Americans -- both individuals and businessmen -- will gain new incentives to work, save, and invest, because of lower taxes and reduced government spending.

These two features of the Reagan program, combined with slower monetary growth and regulatory reform, are expected by the White House to produce lower inflation, faster economic growth, and lower interest rates in the years ahead.

In 1983, for example, the White House foresees real economic growth of 4.6 percent (compared with an estimated 2.6 percent this year); the consumer price index rising at 5.6 percent (now running 8 to 9 percent); and interest rates on 91-day Treasury bills averaging 7.5 percent, about half the current level.

For these optimistic results to be achieved, the new tax savings about to be enjoyed by upper-income Americans and by business would have to be channeled into savings and investment, not consumption.

White House officials assume that millions of lower-income Americans will use their tax savings to pay bills or buy consumer goods. This consumption impulse, the administration believes, will be more than offset by investment and savings at the upper end of the scale.

In summary, Mr. Reagan -- fresh from his latest triumph in Congress -- faces two economic uncertainties:

* He must convince Americans that further sharp budget cuts must be made in social programs, possibly including social security, in order to achieve a balanced budget.

* He must be right in his expectation that his massive income tax cuts will spur investment and healthy eco nomic growth rather than feed inflation.