A Washington think tank proposed capping annual Social Security benefits at $100,000 for couples as a way to shrink a looming deficit in the retirement trust fund.

The idea might sound reasonable enough: Only the wealthiest Americans can collect $100,000 a year from Social Security, a federal program that was meant to ease poverty, not pad wealth.

But the “Six Figure Limit” idea has drawn swift rebukes from retirement advocates, who see any cap or cut in Social Security benefits as a slippery slope.

The March 24 paper comes from the Committee for a Responsible Federal Budget, a centrist, nonpartisan think tank in the nation’s capital. It suggests a $100,000 cap on the total annual benefit for a couple at full retirement age, and a $50,000 limit for a single retiree, starting this year.

“This is for people who already have millions and tens of millions in assets,” said Marc Goldwein, senior policy director at CRFB.