The planned rise in business rates will kill off a third of independent retailers, 'Queen of Shops' Mary Portas has warned the Government.
The retail expert, once hired by David Cameron to find a way of saving Britain's high streets, branded the looming hike "madness", and urged Prime Minister Theresa May to scrap the system completely.
She said the controversial revaluation would be the worst blow to shops since the 2008 crash.
Portas has added her voice to a growing number of business figures speaking out in protest at the plans.
Writing in the Daily Telegraph, she said businesses risked being "destroyed" by increases in their bills of up to 245%.
She said: "In 2011 I was commissioned by the Government to look at how we could save our high streets.
"Six years on and we were really making progress. So it's strange to watch our leaders preparing to impose a new business rates revaluation that will cripple high street shops.
"The tax bill, which will hit retailers from April, will be the single biggest blow to independent shops since the financial crisis.
"I would estimate that at least a third of them will die off."
The Government has said the rates, which are calculated on the rental value of commercial property, will decrease for many businesses due to a fall in property values.
Portas warned that a punitive rise will lead to the return of "clone towns" in which "the only 'mix' will be of charity shops, bookies and Costa".
She said: "I am calling on (Communities Secretary) Sajid Javid, (Business Secretary) Greg Clark, and Theresa May to stop this madness before it destroys everything we've been fighting for."