The government's pension insurance agency remains deeply in the red and expects things to get worse as it assumes responsibility for more retirement benefits that had been promised by airlines and companies in other troubled industries.

In its annual report to Congress, the Pension Benefit Guaranty Corp. reported that the value of pension benefits it is obligated to pay exceeded its assets by $22.8 billion at the end of fiscal 2005. That figure is a slight improvement from a year earlier, when the shortfall was $23.3 billion.

PBGC officials said unspecified "events subsequent to the fiscal year," which ended Sept. 30, will make matters worse. Had those events occurred before Sept. 30, the deficit would have been $25.7 billion, the agency said.

The PBGC counts as liabilities pensions it has taken over plus those that it probably will take over. It is possible that the unspecified events mentioned by the PBGC include the recent bankruptcy filing by autoparts maker Delphi Corp.

Delphi "looks like the right order of magnitude" to account for the jump after Sept. 30, said Julia L. Coronado of benefits consultants Watson Wyatt Worldwide in Arlington.

In a statement accompanying the report, the agency's executive director, Bradley D. Belt, warned that the PBGC's financial health is not improving.

"The money available to pay benefits is eventually going to run out unless Congress enacts comprehensive pension reform to get plans better funded and provide the insurance program with additional resources," Belt wrote.

The agency said it added $4 billion in losses from completed and probable pension takeovers for the fiscal year while collecting $1.5 billion in insurance premiums from employers. The agency earned $3.9 billion in investment income. Also, rising interest rates, which cause the present value of future benefits to decline, resulted in a $2.3 billion reduction in liabilities.

The overall result was a gain of $529 million, the PBGC said.

Because of Chapter 11 bankruptcy filings by Delta Air Lines Inc. and Northwest Airlines Corp., some analysts had expected the agency to report sizable losses. The slight gain on the agency's books "is far better than the $10 billion or more loss that I expected," said Douglas J. Elliott, president of the Center on Federal Financial Institutions, a research group. However, the PBGC "does not appear to have turned a corner yet in the real world," he said.

In fiscal 2005, the PBGC took over 120 pension plans from employers with assets totaling $10.5 billion and liabilities totaling $21.2 billion, the agency said. However, all but $300 million of the liabilities were already on the PBGC's balance sheet at the end of last year.

The agency reported that it regards another $108 billion in claims, beyond those already booked or probable, as "reasonably possible" from companies that are rated below investment grade.

The PBGC estimated total underfunding throughout the private pension system at $450 billion.

The PBGC, which insures 44 million workers and retirees in more than 30,000 pension plans, pays pension benefits when employers cannot, up to about $45,000 a year for a 65-year-old retiree. When it takes over a plan, it assumes the liabilities and takes ownership of the assets, and must make up the shortfall, which can be quite large. Where the plan promised pensions higher than the PBGC limit, workers and retirees can lose some or all of the excess.

Aided by the stock market run-up of the 1990s, the PBGC posted a surplus of $9.7 billion in 2000. But the wave of bankruptcy filings in the steel, airline, mining and auto-parts industries, and the stock market plunge after 2000, quickly wiped out that cushion.