Yahoo said in a filing Mayer will receive the severance pay if she lost her job "without cause".
Verizon hasn't yet specified whether Mayer will continue to lead Yahoo after the deal. She joined the firm as chief exec in 2012 but has come under fire for failing to turn around the business.
There had been speculation that Mayer would depart once the deal was announced, however, in a note to employees, she said she would remain in place.
The deal with Verizon is expected to close in the second quarter.