(Reuters) - U.S. Vice President and Democratic presidential candidate Kamala Harris' proposed corporate tax hike ahead of the November Presidential elections could lower earnings for companies on the benchmark S&P 500 index by about 5%, analysts at Goldman Sachs said.

Last month, Harris proposed raising the corporate tax rate to 28% from 21% and ensure "big corporations pay their fair share," if she wins the election against Republican rival Donald Trump.

Goldman estimated that at a 28% taxation rate earnings of S&P 500 companies would take a 5% hit.

Adding taxation of foreign income and an increase in the alternative minimum tax rate to 21% from 15% could reduce earnings by as much as 8%, the analysts said.

On the other hand, Trump's proposed relief on the federal statutory domestic corporate tax rate to 15% from the current 21% would "arithmetically" boost S&P 500 earnings by about 4%.