The Carter Administration and key House committee leaders agreed yesterday on the outlines of a truncated welfare revision bill costing half as much as the president's stalled $20-billion-a-year measure.

House Ways and Means Committee chairman Al Ullman (D-Ore.), emerging from a meeting with two Cabinet members, Massachusetts Gov. Michael Dakakis and senior House members, said the parties had agreed to make an "intensive effort" to get some measure of welfare revision through Congress this year, even though the president's massive $20 billion bill is [WORD ILLEGIBLE] because of its costs.

The key provisions include:

National minimum benefits for Aid to Families with Dependent Children (AFDC) of about $4,200 (65 percent of poverty line) for a family of four, composed of cash payments plus food stamps. (About 10 states now pay less than this amount.

700,000 public service jobs and training opportunities for the principal wage-earner in a welfare family if he or she is able to work.

Continuation of state and local administration of AFDC program.

An increase in the existing earned income tax credit (a 10 percent Treasury payment on the first $4,000 of private-job wages earned by a low-income family).

The cost of the above program is estimated at $9 billion to $12 billion a year, above existing federal costs, of which $1.5 billion to $2.5 billion would be in fiscal relief to the states through federal assumption of part of the welfare costs now borne by the states.

The administration bill provided more jobs (1.1 million as approved by a welfare subcommittee) and more fiscal relief to the states (about $3.2 billion) and also provided welfare to single persons and childless couples, thus costing $8 billion or so more.

The new bill must now be drafted, reviewed by the principals and then approved by three committees and both chambers. Yesterday's agreement after weeks of negotiation, however, is the first sign in months that there is any chance this year for a welfare bill. House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) had told administration and House leaders two weeks ago that unless they could get together on a compromise, there wasn't any point in bringing up a bill this year.

Secretary of Health, Education and Welfare Joseph A. Califano Jr. said he hoped the bill could be put before the House Welfare subcommittee within a few weeks.