The Senate Finance Committee yesterday gave President Reagan almost exactly the tax-cut bill for which he had asked, including a 25 percent reduction in individual income tax rates over 33 months beginning Oct. 1 and provisions that would cut business taxes 40 percent by 1985.

The tax bill, approved 19 to 1 by the Finance Committee, gives the president more than he asked for; as the senators voted to cut the windfall-profits tax on a part of the nation's oil production and to begin "indexing" the individual income tax automatically in 1985 to make allowance each year for inflation.

Reagan has said in the past that he opposes the windfall-profits tax and supports indexing, but the Treasury Department was obliged yesterday to oppose the committee actions on both issues because of their drain on the tax receipts the administration needs if it is to achieve a balanced budget by 1984.

The committee bill would aid business mainly by letting it deduct costs of equipment, buildings and vehicles much faster than it can now, in hopes of spurring expansion and job creation.

There also are provisions to reduce the estate tax so that it applies to less than 1 percent of the population, to reduce the marriage penalty under which two workers pay more if married than they would if single and to liberalize provisions under which income can be set aside tax free in savings and retirement accounts.

Individuals would receive a 5 percent rate cut in the last three months of 1981, and 10 percent cuts on July 1 in each of the next two years.

But for households in the low- and middle-income brackets, these cuts would be barely enough to offset already scheduled increases in Social Security taxes and the effect of inflation, which steadily pushes all taxpayers into higher brackets.

The bill's size and its embrace of "supply-side" economic theory make it "a clear and unmistakable break with the past," said Sen. William V. Roth Jr. (R-Del.), a committee member and an author of the multiyear-tax-cut theory built into it.

Committee Chairman Robert J. Dole (R-Kan.) said he hopes to persuade House leaders to complete work on the bill next month to permit Reagan to sign it by Aug. 1. If House leaders can't meet that schedule, Dole is prepared to have the Senate bill put before the House directly, he indicated. p

Democrats on the House Ways and Means Committee, however, showed no signs of falling in line, and yesterday offered a two-year alternative income-tax-cut plan that would be more generous to low- and middle-income taxpayers than the administration-Finance Committee bill.

After almost four days of debate, the Finance Committee produced a bill that closely matches the dollar figures in the Reagan proposal. Preliminary estimates show a $37 billion cut in fiscal 1982, $91.7 billion in fiscal 1983 and $149.2 billion in fiscal 1984, all slightly less than the administration originally sought. The estimated cut in fiscal 1985 would be $183 billion and $226 billion the following year, slightly above administration targets.

When the cuts were fully effective, the proportion of federal taxes paid by corporations would drop from 11 percent now to 7 percent.

Sen. George J. Mitchell (D-Maine) complained that the Senate bill is "overwhelmingly favorable" to the over-$50,000 income group, and offers "no relief whatever to those earning below $20,000. . . . There is nothing for those who need it most."

"The working population of this country is not going to be fooled," said Sen. Bill Bradley (D-N.J.). Mitchell, however, voted for the bill. Only Bradley voted against it.

Democratic leaders in the House will try that theme again, as they push for their tax alternative.

The House Democrats would cut tax withholding 5 percent on Oct. 1 and an additional 10 percent on July 1, 1982, exactly the same as Reagan. However, there would be no third cut on July 1, 1983, and the maximum tax of 70 percent on investment income would be lowered by 50 percent in two steps rather than the one in the Senate bill.

At the same time, the Democratic plan also includes three provisions not in the Reagan proposal:

An increase in the "zero-bracket amount" from $2,300 to $2,500 for single individuals and from $3,400 to $3,800 for couples filing joint returns. Raising the zero-bracket amount, or tax threshhold, which used to be known as the standard deducition, would particularly benefit the generally lower income taxpayers who do not itemize deductions.

But it also would have the effect of raising each tax bracket by $200 or $400, and so would lower the tax bill of everyone, including those who itemize. $4

An increase in the earned income credit available to low-income workers with dependent children. The present credit, equal to 10 percent of earned income up to $5,000, and which phases out between $6,000 and $10,000, would be raised to 11 percent and be phased out between $8,000 and $12,000.

An increase in the maximum tax credit for child care from $800 to $1,200. The proportion of expenses allowed as a credit would rise up from 20 percent to 25 percent, while the maximum for expenses would be increased from $2,000 to $2,400 for one child and from $4,000 to $4,800 for two or more children.

Finally, the Democrats want to go the Republicans one better in providing a deduction for couples in which both spouses have incomes.

This so-called marriage penalty deduction would be equl to 10 percent of the income of the spouse with the lower income up to a maximum of $5,000. Reagan proposed a 5 percent deduction for 1982, rising to 10 percent in 1983, with a $1,500 and $3,000 maximum, respectively.

In calendar 1982, the Democrats would cut personal taxes by $40 billion, compared with $35.7 billion for Reagan. In dollar terms, nearly 80 percent of next year's cut would go to taxpayers with incomes below $50,000, compared with 65 percent under the administration proposal.

"The Democratic tax bill is fairer to individuals than the president's package, especially to working American families," said Ways and Means Chairman Dan Rostenkowski (D-Ill.). "They are the people who doubted us last November. They are the people we must convince that Democrats are very concerned about them and this country's economy."

A fear of large deficits and continuing inflation led the Democrats to offer only a two-year bill for personal tax cuts. In fiscal 1984, the Democrats' personal cuts would total $88 billion, compared with $112.3 for Reagan's version. But Rep. Ken Holland (D-S.C.), head of the task force that developed the alternative, said the Democrats were not ruling out a third-year tax cut.

"If the economic projections of the administration turn out to be correct, I see no reason why we can't go into a third year or even a fourth year," he said.

The same pressure worked on Finance Committee members this week as they struggled to provide tax cuts for "needy" special interests without exceeding the administration's limits.

The controversial indexing plan represents a tremendous potential tax loss: adjusting tax returns for inflation last year would have cut Treasury receipts by $11 billion, ccording to Senate figures.

Sen. William L. Armstrong (R-Colo.) proposed to adjust personal income tax rates, the personal exemption, standard deduction, capital gains and estate and gift taxes downward to offset increases in the goernments consumer price index. The starting date would be January, 1985, to avoid a conflict with the Reagan promise of a balanced budget in fiscal 1984.

Armstrong's proposal was adopted as a committee amendment, not part of the tax bill, and will be subject to a separate Senate vote.

The committee also adopted a reduction in the windfall-profits tax, which was watered down by its author, Sen. David L. Boren (D-Okla.), to stay within the revenue limits. Boren's initial proposal was approved by the committee Wednesday, then defeated when Dole persuaded several senators to change the stand.

Boren's compromise would cut the 30 percent windfall tax on newly discovered oil to 15 percent in four steps between 1983 and 1986, with the loss in revenues rising from $200 million in 1983 to $1.3 billion in 1986.