The Social Security tax was signed into law in 1983 by then-President Ronald Reagan with the intention of strengthening the program's trust fund.
The law allows up to 50% of a recipient's Social Security benefits to be taxed if that person's income falls between $25,000 and $34,000, and when the person's income is over $34,000, up to 85% of it can be taxed.
The Republican Party platform, approved last summer and written in part by Trump, prohibits cutting Social Security or Medicare and rules out hiking the age for retirement.