The draft tax legislation being prepared for the Senate Finance Committee does not call for significant amounts of new revenue from outside the income-tax system, congressional sources said yesterday.

Such sources of revenue, such as a gasoline tax, oil-import tax or higher excise taxes, had been considered possible ways to keep the legislation from bringing in less revenue than the current tax system while lowering rates for individuals and businesses.

The draft legislation also is said to include effective dates that are later than those in the tax bill passed by the House last December.

The Senate bill is in preliminary form, and probably will be presented for approval to committee Chairman Bob Packwood (R-Ore.) Monday, sources said. Many changes still could be made in the proposal before it is presented to the full committee as a starting point, probably late next week or early the following week.

But at this point, with the draft 99 percent complete, the bill raises money to pay for lower rates almost entirely from the income tax. Aides earlier had said the bill would not include a tax on imported oil; now it appears other new nonincome taxes have been excluded as well.