Tesla said Elon Musk’s record $56 billion pay package isn’t excessive, adding that a new compensation plan would be costlier.

The electric vehicle company on Monday reaffirmed its support for Mr. Musk’s 2018 pay package, dismissing top proxy adviser ISS’ criticism against the plan last week.

The car giant said ISS, which urged shareholders to reject the pay plan, misunderstood the package. According to Tesla, if shareholders reject the $56 billion deal at the June 13 shareholder meeting, any new pay package with similar options would cost more.

“A functionally equivalent grant of new options could result in an accounting charge of more than $25 billion compared to the $2.4 billion charge originally recognized for the 2018 award,” it said.

Finally, Tesla argued that the 2018 pay package incentivized Mr. Musk to create “tremendous value” for shareholders. The pay plan rules required Tesla to hit certain benchmarks before the CEO could cash out.

Tesla’s board of directors voted to approve the package six years ago. However, a group of rogue shareholders sued the company in Delaware to block the payout. This past January, a Delaware judge officially blocked the package, ruling that Mr. Musk had too much control over the board for the pay deal to be legitimate.

In response, Mr. Musk lashed out at the judge, Kathaleen McCormick, vowing to move Tesla’s incorporation to Texas and urging shareholders to reaffirm the pay package despite her ruling. Tesla shareholders will begin voting ahead of the company’s annual meeting next week.

Mr. Musk CEO has tried to incentivize shareholders to vote for his pay package by offering a lucky voter a chance to win a guided tour of a Tesla Gigafactory with him.