Washington — For most Americans, next year's tax cut will turn out to be less than the highly touted 10 percent slash in income tax rates scheduled to begin July 1, 1982.
President Reagan insists that the 10 percent cut will not be postponed, so some extra dollars certainly will line family pocketbooks next year.
However, other things are happening that will nibble away at the overall tax reduction for which Americans had hoped.
Social security taxes will rise on Jan. 1, hiking the maximum payroll tax by first $32,400 of an individual's earnings, up from $29,700 this year. People with smaller incomes also will pay higher social security taxes, because the tax rate goes up from 6.65 percent this year to 6.7 percent in 1982.
That means a payroll tax nearly $100 higher, says the Social Security Administration, for an average worker earning $13,729 this year and $15,045 in 1982. As the income climbs, so does the extra tax.
Two-income families are doubly hit. Employers also pay the higher tax, a labor cost that often is passed on to consumers in the form of higher prices.
Apart from social security taxes (over which he has no control), President Reagan remains stubbornly opposed to additional tax hikes. He came into office pledging lower taxes and smaller budget deficits, aiming at a balanced budget in 1984.
Recession, combined with huge tax cuts and higher defense spending, are turning Mr. Reagan's budget hopes into a nightmare, with some congressional experts forecasting a deficit of more than $200 billion in fiscal 1984.
But the President's top economic aides are trying to persuade him that the Treasury must collect extra tax revenues.
Publicly, at least, the President will countenance discussion of nothing beyond $22 billion worth of tax boosts - styled ''revenue enhancements'' by the White House - over the next three years. These extra revenues - $3 billion in fiscal 1982, $8 billion in 1983, and $11 billion in 1984 - would largely be achieved by tightening up tax-paying provisions for corporations.
Mr. Reagan also suggests that Americans who benefit from federal assistance - such as boat owners and barge operators who receive services from the Coast Guard and maintenance of waterways - should be charged ''user fees,'' a proposal initially shot down by Congress early in 1981.
Even if Congress went along with the $22 billion package, it would fall far short of lassoing the budget deficits and beginning to bring them down.
Thus a search is on for tax increases that Reagan will accept, as a first step toward getting them enacted into law by Congress. High on the list is a windfall profits tax on natural gas, if the President decides to speed up the deregulation of this fuel, as he did with oil.
A windfall profits tax on oil brings billions of dollars yearly into the Treasury and a similar levy on natural gas, according to Treasury Secretary Donald T. Regan, might yield $10 billion to $20 billion yearly.
Reagan, however, opposes such a tax. In a note to Rep. Glenn English (D) of Oklahoma, the President said he would veto a windfall profits tax if Congress passed it. How to get around that pledge?
''I wonder,'' said Secretary Regan at one point, ''how the letter would taste torn up and covered with mustard?'' Reportedly Mr. English was not amused. In any event, Reagan's aides apparently have not persuaded Reagan to accept a windfall tax on gas.
Other possibilities under consideration - by administration aides and not necessarily by the President - include raising the present 4-cent-a-gallon federal tax on gasoline.
An import fee on foreign oil, serving the twin aims of raising money for the Treasury and fostering energy conservation, has been mentioned. Congress killed an oil import fee advanced by former President Carter.
Higher so-called ''sin'' taxes on alcoholic beverages and tobacco also are proposed as part of a tax-raising package.
Taxes listed above are ''regressive,'' falling most heavily on lower-income Americans. People at all income levels would pay the same tax on gasoline, for example, unlike the ''progressive'' income tax, which rises as income goes up.
This regressivity almost certainly would be lessened, by granting income tax credits to low-income citizens or - in the event of a broader excise tax - by excluding food, medicine, and other necessities.