Senate Finance Committee Chairman Bob Packwood (R-Ore.) said yesterday that his tax-revision package could include tougher limits on deductions for consumer interest payments than those approved last year by the House.

In a rare public preview of the draft tax plan that the senator and his staff are close to completing, Packwood also said the proposal would cut back on tax-deferred retirement savings plans, but by less than the House measure did. He also said write-offs for investment expenses would be more generous than those in the House bill and as beneficial to business as President Reagan wanted.

Packwood predicted that a tax bill would be passed by Congress and be on Reagan's desk for signature by Aug. 15. Separately, Senate Majority Leader Robert J. Dole (R-Kan.) said yesterday that he wanted the Senate to complete deficit reduction before starting debate on tax overhaul.

"The way to get tax reform done this year, if I were the president, is to keep pushing us and to sit down with us on the deficit," Dole said in a luncheon speech. "We'll do deficit reduction and tax reform in that order."

His remarks reflected the substance of a letter signed by 50 senators asking Reagan to delay tax revision until the White House and Congress had worked out an agreement on reducing the budget deficit. Dole did not sign the letter, and aides pointed out that if the Senate can approve a congressional budget resolution by the April 15 deadline, Dole could achieve his goal without affecting the tax bill.

Packwood responded to the letter yesterday by saying Dole, as majority leader, has the power to decide whether tax revision is brought before the Senate.

Once the legislation is approved by the Finance Committee and placed on the Senate calendar, "If Bob Dole chooses not to call it up, it won't come up. If he chooses to call it up, it will," Packwood said.

In a speech to an insurance group, Packwood hinted at several items that will be included in the draft, which is expected to be finished next week:

*House-passed limitations on consumer interest deductions -- which permit deduction of interest on mortgages for up to two houses, plus an amount of interest equal to the taxpayers' investment income, plus $20,000 -- may be tightened if final computer analyses show that the package would bring in less revenue than the current tax system. "You are aware of the enormous amount of revenue involved in the limitation on consumer interest," Packwood reminded his audience.

Late yesterday, aides said the revenue estimates had been completed but declined to say whether the package was "revenue neutral." They said there would be some modifications to the package, but cautioned against drawing the conclusion that the plan would bring in less revenue than the current tax code.

*Limits on 401(k) plans, which permit employes of companies that offer such plans to save up to $30,000 per year for retirement while delaying payment of taxes on the money, will be less severe than the $7,000 per-year ceiling the House bill would impose on employe contributions. And Packwood said he did not expect his bill to restrict contributions to tax-deferred Individual Retirement Accounts for those who already have 401(k) plans, a controversial feature of the House bill.

*What Packwood called "normal" fringe benefits, such as health-insurance premiums and life-insurance policies provided by employers for employes, would remain untaxed. But his remarks left open the possibility of taxation of other benefits such as school tuition and group legal services paid by employers.

*Like the House legislation, the Packwood plan would give a large tax cut to lower-income taxpayers and would not change the size of the tax cuts -- ranging from 5.6 to 9.9 percent for middle- and upper-income brackets -- for other income categories.

Separately, sources indicated that the package was likely to cut back sharply or repeal the tax credit for rehabilitation of old and historic buildings, and to end a tax shelter under which investors in real estate can build up large paper "losses" they use to shelter income.