As a presidential candidate in 1980, Ronald Reagan repeatedly said that U.S. business needed tax incentives for investment. As an incumbent in the 1984 campaign, he said his 1981 tax cut had accomplished that, inducing companies to expand investment and spur the recovery.

Lower corporate income taxes were one of Reagan's proudest achievements. As a share of the economy, they hit a historic low of 1.1 percent in 1983. As recently as 1978 the share had been 2.9 percent.

But Reagan's fiscal 1986 budget, being submitted to Congress today, says that trend is going to be reversed.

The budget says that taxes from the business sector will rise to 2 percent of gross national product by 1988. As a share of total revenues, corporate income taxes are projected to go from 6.2 percent in 1983 to 10.4 percent in 1988.

Individual income taxes, however, would climb only slightly in proportion to GNP.

Revenues from personal income taxes will be $140.4 billion less than they would have been in 1986 if the tax cut hadn't been passed.

The biggest change in the tax-receipts projections of the Reagan budget is in business taxes. Like the earlier decline in the corporate share, the anticipated increase is due in part to changes in the economy overall. But it also reflects how the effects of the 1981 cut have been reversed by tax legislation supported and signed by the president.

"Most of what the 1981 law gave business has been taken away," said Emil Sunley, director of tax analysis for the accounting firm Deloitte Haskins & Sells and formerly deputy assistant treasury secretary for tax policy during the Carter administration.

The 1981 legislation cut corporate taxes by $54.9 billion from their expected fiscal 1988 level. But it was quickly followed by the Tax Equity and Fiscal Responsibility Act of 1982, which added $42.9 billion in tax revenues for the same year; last year's Deficit Reduction Act, which increased business taxes $9.8 billion, and various other bills containing cuts or increases.

Overall, the net corporate tax reduction for 1988 was $4.3 billion.

Those figures don't include the expected revenue from the administration's anticipated tax-simplification proposal, not yet in final form. But as proposed by the Treasury Department, the plan would raise the corporate sector's taxes by 26 percent.

Overall, for individuals and corporations, in 1988 the benefits of the 1981 cuts would be $283 billion, but the various bills enacted since then would take back $115.8 million.

The budget also shows the difficulty the administration has had in holding the total tax burden constant. Despite frequent promises by administration officials that taxes would never exceed 19 percent of GNP, revenues now are projected to rise to 19.3 percent by 1988 and 19.5 percent by 1990. The increase is due mostly to the rise in business taxes.

Reagan's budget includes several legislative proposals that would affect tax revenues, but not by much. The net effect of the tax measures would be a $200 million revenue increase in 1986 but a loss in later years as proposals such as tuition tax credits became effective.

Tuition tax credits, which are making their third appearance in the Reagan budget, are one of several proposals that have been made a number of times already. Also included are enterprise zones for distressed urban areas, proposed in the last four budgets, and tax-free savings accounts for children's college educations, proposed in the last three budgets.

None of these measures has gone anywhere in Congress. The same is true for two other repeats in the 1986 budget plan, partial taxation of employer-paid health-insurance premiums and expansion of Individual Retirement Account coverage to homemakers.

Those two are not specifically proposed in the 1986 budget because, according to the budget document, they will be included in legislation the administration will propose later this year to simplify the tax code. This marks the first promise the administration has made about what will appear in the tax-simplification bill.

The administration also includes a few new proposals to raise revenue. It wants to make taxpayers and tax-exempt organizations pay $100 for any ruling from the Internal Revenue Service about the legality of their tax status or use of tax breaks.

It also proposes increasing the dependent-child-care credit to up to 40 percent of day-care expenses for low-income taxpayers, but phasing out the credit as income rises from $10,000 to $60,000.

The budget document does not say how its socially motivated tax proposals, such as the education savings account, square with the idea of tax simplification. Streamlining the tax code, administration officials have said, is intended to let individals make economic decisions based on merit rather than the provisions of the tax code.