Congress is not going to pass a housing authorization bill this year, according to Sen. Jake Garn (R-Utah), chairman of the Senate Banking, Housing and Urban Affairs Committee.

The Senate has too many other, more pressing items facing it this fall, Garn said. "We passed the appropriation bill," so the authorization measure isn't critical, he added.

In addition, Sen. William L. Armstrong (R-Colo.) has vowed to block floor action on the bill unless substantial changes are made "and if I satisfied him, there are two or three others who would filibuster" because of the changes, Garn said.

"There isn't going to be a housing bill this year," he said.

Congress also failed last year to approve a housing authorization bill, leaving the nation without a low-income housing production program for the first time in 45 years. Advocates of social welfare programs bitterly accused congressional Republicans and the Reagan administration of allowing the bill to die in order to save money.

In the House, which passed its authorization measure in July, Banking Committee Chairman Fernand J. St Germain (D-R.I.) is threatening to hold up a bill providing additional money for the International Monetary Fund until the Senate acts on the housing authorization bill. The leadership of the Republican-controlled Senate has repeatedly said they intend to bring the bill to the floor, but they have done so only once and then quickly pulled it back after brief debate.

Sen. John G. Tower (R-Tex.), chairman of the Housing subcommittee, was still saying this week he plans to "do everything I can . . . to try to get the authorization bill up. Hopefully, we can act on it."

However, he went on, "if we fail to, I hope that, in connection with the . . . extension of the FHA programs, perhaps we can at least tack on some of the things on which there is consensus agreement" and put off others, and thus get "some kind of authorization passed."

But Garn, who appeared at a conference in Annapolis sponsored by the Federal Home Loan Mortgage Corp. last weekend, said St Germain "shouldn't be holding the IMF bill hostage. I can't produce a housing bill. If I could accommodate him, I certainly would."

Not only is the Senate very busy, Garn said, but there are "such large differences" between the Senate and House versions that it would make a "very difficult conference."

The appropriation measure signed by the president during the summer does contain money for 5,000 units of new public housing. In addition, that bill included funds to continue the Section 202 program for the elderly; the Section 8 rental subsidy for existing housing; the Section 8 moderate rehabilitation, and the Community Development Block Grant and Urban Development Action Grant programs.

But the numbers of units provided for in the assisted housing programs are far below what critics have said are necessary.

Death of the authorization bill would allow the Department of Housing and Urban Development to implement or continue a number of money-saving programs:

* Appropriations conferees dropped language that would have prohibited HUD from selling any of its Section 202 loan portfolio without congressional permission. Under this program, the department makes direct loans to nonprofit organizations to provide housing for the elderly or handicapped.

* The ceiling on the share of income that a subsidized tenant would have to contribute toward his rent would remain at 30 percent. That ceiling had traditionally been 25 percent

* The department may proceed with its plan to change the formula for calculating fair market rents in the Section 8 rent subsidy program for existing housing. The change is expected to result in substantial cost-reductions in the program.