The CBI is urging 190,000 companies to let its employees work from home on 23 June in order to enable them to vote in the EU referendum.
Carolyn Fairbairn, CBI director-general, said that the referendum will be the "biggest decision that most of us will get to vote on in our lifetimes".
She said: “The decision on whether we choose to stay in the EU will have serious implications for our economy, jobs and the opportunities for young people in the years ahead and it’s important everyone has their say.
"Only by having a clear result, where everyone’s voice has been heard will we be able to build stability and move on after the vote, whatever the outcome."
Fairbairn went on to say that firms should show greater flexibility to ensure their employees vote in the upcoming referendum.
She added: “Firms have an important role to play: where possible, they should do what they can to help their staff have the time to cast their vote.
“That might mean showing greater flexibility on when they expect employees to arrive at work and leave for the day, or perhaps see how shift patterns can be adjusted as a one-off.”
Brexit group Vote Leave dismissed CBI's move as a "desperate" effort.
A spokesperson told City A.M.: "The move shows desperation of the CBI and its Brussels cronies to try and get people to vote remain."
The deadline to register to vote ends at 11.59pm today.