In the July heat of the all-night session of the House-Senate conference committee that produced the final version of the $749 billion tax cut, lobbyists from the Treasury Department had one central goal: Whenever possible, postpone revenue losses to 1985 and 1986.

The purpose of the strategy was to minimize the results of the "bidding war" on President Reagan's promise to balance the budget by 1984. With help from a cooperative group of congressmen, the strategy was largely successful as a collection of fiscal time bombs was set to go off after the 1984 presidential election year.

However, with the president's acknowledgment that the goal of balancing the budget in 1984 has gone down the chute in a deteriorating economy and with the widely held view that the deficit in 1984 could reach $100 billion or more, the consequences of the tax cut in 1985 and 1986 have become more significant.

The overall numbers, according to estimates of revenue losses by the Joint Committee on Taxation, show the Treasury losses going from $149.96 billion in 1984--a factor many economists contend is a key reason for the inability of the Reagan administration to balance the budget that year--to $199.31 billion in 1985.

This growth of revenue losses amounting to just under $50 billion is more than matched by estimates for the next year, when total lost revenues are expected to shoot up to $267.6 billion. In other words, the annual cost of the tax bill to the Treasury from 1984 to 1986 will increase by $118 billion.

In the administration's early scenario, the drain on federal revenues actually was to become a source of a revitalized economy in which industrial expansion, productivity growth and a sharp increase in the the job market would result in a growing revenue base. That scenario has yet to materialize.

Among the items in the tax bill that either become effective in 1985 and 1986 or have only small fiscal consequences until those "out-years" are:

* Indexing. Starting in 1985, income tax brackets, the standard deduction (zero bracket amount) and the personal exemption will be adjusted annually according to changes in the Consumer Price Index, one measure of inflation. According to the joint committee, the revenue losses from this provision in 1985 will be $12.9 billion and in 1986 $35.8 billion.

* Charitable deductions. Congress added a deduction for users of the "short form," allowing a line-item deduction for charitable gifts. In the initial years, however, there are restrictions setting both a ceiling on the deduction and a percentage limit on the amount of the gifts that can be deducted. In 1985 these limits are partially eliminated and in 1986 they are completely eliminated. The result is that estimates of revenue losses triple from 1984 to 1985, going from $219 million to $681 million, and in 1986 they more than triple again, shooting up to $2.7 billion. This provision dies in 1986, but, given the strength of the charity lobby in Congress, everyone expects it to be reenacted or replaced with something equivalent.

* Employe stock ownership plans. The legislation shifts the current investment tax credit for contributions to employe stock ownership plans to a payroll-based credit with a ceiling set at 0.5 percent of a company's wages in 1983 and 1984, growing to 0.75 percent in 1985 through 1987. In terms of revenue losses, this provision will go from $61 million in 1983 to $628 million in 1984. It will more than double to $1.7 billion in 1985 and go to $2.2 billion in 1986.

* Interest exclusion. Starting in 1985, taxpayers will be able to exclude 15 percent of their interest income, up to a ceiling of $3,000 for a single return and $6,000 for a joint return. This provision is far more advantageous for persons with large savings than the current system allowing a straight exclusion of the first $200 ($400 for a joint return) of dividend and interest income, which favored small savers. In terms of revenue losses, however, it will result in a loss of $1.1 billion in 1985 and $3.1 billion in 1986. Along with the expansion of Individual Retiremement Accounts and the stock ownership plan provision, it is one of the major reasons that the estimates of the losses from the "savings incentives" in the bill will grow from $247 million in 1982 to $8.4 billion in 1986, according to the joint committee.

* Estate taxes. The legislation effectively wipes out estate tax liability for all but a tiny fraction of the wealthiest persons. In a phased process, the percentage of estates subject to taxation will drop from the current level of about 2.8 percent to 0.3 percent by 1986. Reduced tax payments because of these provisions will go from $204 million in 1982 to $5.6 billion in 1986.

* Weakening of the windfall profits tax on oil. In a phased pattern very similar to the step-by-step reduction in the estate tax, revenue losses resulting from lowered taxes on elements of the oil industry will grow from $1.3 billion in 1982 to $3.6 billion in 1986.