Social Security benefits could be cut by 25 percent if Congress does not act soon, Social Security Administration Chief Actuary Stephen Goss warned a Senate panel Wednesday.

“Changes are needed soon to avert trust fund reserve depletion and an abrupt reduction in the level of benefits,” Goss said in prepared remarks to the Senate Finance Committee.

He noted trust fund reserves for disability Insurance are expected to be at zero by late 2016.

The actuary said one possible solution would be to devote some of the payroll tax from Old Age and Survivors Insurance to disability, but even then he cautioned one or both of the reserves would be without money by 2033. (Meanwhile, a representive from the conservative Heritage Foundation testified in written testimony before a Congressional Joint Economic Committee that the Social Security spousal benefit should be eliminated.)

Emphasizing the importance of Social Security to the elderly, Goss said one-third have little retirement income outside of it.

The average retiree benefit was $15,240 in 2013, about 42 percent of the average taxable earnings of workers that year.

Goss said factors leading to the shortfall in the reserves include longer lives, the huge baby boomer population coming into retirement and a precipitous, permanent decline in the historic birth rate from three children per woman to two after 1965, which has led to a lower ratio of employed workers to support retiree benefits than previously.

While contending the talk of a population-wide retirement crisis is overblown, Jason Fichtner, a researcher at the conservative outpost of George Mason University’s Mercatus Center, said Social Security reform must begin immediately.

At the session, Finance Committee Chairman Sherrod Brown (D-Ohio) predicted Congress will reallocate money in the trust fund to help keep disability insurance going past 2016.

Speaking on ideas to improve the financial health of Social Security, the senator said: “Raising the retirement age, increasing taxes and delaying cost-of-living adjustments are blunt instruments that harm low income workers.”

After the hearing, he told Financial Advisor magazine he does not think its “imminent “ that Congress will approve adjustments to boost the trust fund.