Trump wants to cut income taxes on Social Security. Here's how that would impact your benefits.

Former President Donald Trump is promising to eliminate taxes on Social Security, a vow aimed squarely at the 67 million Americans who receive monthly benefit checks from the retirement and disability program. 

"Seniors should not pay taxes on Social Security and they won't," Trump said at a Wednesday campaign rally in Harrisburg, Pennsylvania.

Such a pledge could be be a potent campaign plank at a time when poverty among seniors is on the rise, according to the National Council on Aging, and the U.S. Government Accountability Office has found millions of older workers are nearing retirement without a penny in savings. Currently, about 40% of Social Security recipients pay federal income taxes on their benefits, according to the agency.