Multimillionaire Boost Juice founder Janine Allis has criticised the federal budget's tax changes, saying they are "just so unfair".

In a social media video, the typically apolitical Allis said Labor's decision to wind back the capital gains tax discount and grandfather negative gearing would "destroy the core of what Australians are".

"I would put my house on the line, I put everything on the line, and then I work my absolute butt off, risk everything, be away from my family, etc," she said.

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"To eventually make a profit and give nearly half to the government?

"Oh my god, that is just so unfair. It doesn't allow you to get ahead, it doesn't inspire you to actually take the risks that you need to take."

The government broke an election promise by moving to replace the capital gains tax discount with a less generous inflation-linked rate and a minimum 30 per cent rate.

Negative gearing will be limited to new builds and no longer apply to any existing properties bought after 7.30pm on May 12.

Both policies are commonly used for property, but the capital gains tax discount can apply to most capital assets, like managed funds, while negative gearing can apply to other income-producing assets like shares.

Allis said she believed the changes would kill ambition to start a business and ward off investment from global businesses.

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"If you tell people on election that you're not going to be touching their negative gearing and capital gains tax, you have to stick with it," she said.

"The reason being is people make decisions in business based on what you tell them. If you don't tell the truth or change your mind, it's too big of a decision.

"I might have misunderstood it, I hope I have, it's not passed but if it does, the unintended consequences of this is horrific." 

Allis is one of the country's most successful self-made entrepreneurs after founding the Boost Juice chain in 2000.

It went on to become a global empire with more than 850 stores across the world.

Allis is the part-owner of Retail Zoo, which is the holding company for Boost Juice, Betty's Burgers and Salsas Fresh Mex.

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A vote in the US House of Representatives that would have forced Donald Trump to immediately end America's war with Iran has ended in a tie.

Three Republicans crossed the aisle to vote with 209 Democrats on a resolution directing the president "to remove the United States Armed Forces from hostilities against the Islamic Republic of Iran".

One Democrat and an independent joined the remaining 210 Republicans to vote no.

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A tied vote in the House means the resolution did not pass.

The three House Republicans who crossed the floor this morning are all facing tight re-election races in November's looming elections.

Earlier this week, Trump lost the support of another Republican in the Senate.

Lisa Murkowski voted against the war for the first time, alongside two other Republican opponents.

Her switch meant legislation to end the war in the upper house failed by two votes.

If the resolution passed both houses, Trump would have no choice but to end the US blockade of the Strait of Hormuz and cease all hostilities with Iran.

The handful of defecting Republicans in a narrowly held Congress should be cause for concern for Trump.

In previous wars, Congress had a habit of rallying around the flag to support it. 

The declaration of war on Japan in 1941 passed the House 388 to one, and in the Senate 82 to zero.

The vote was held an hour after President Franklin Roosevelt's "day that will live in infamy" speech.

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But Trump has done very little to convince the American people of the value of the war with Iran.

Democrats are tearing into Trump over the war and its cost.

"It's been 76 days since Trump launched his illegal war in Iran, and the Administration is still refusing to share with Congress or the public an official legal rationale for the conflict—all while pushing for $US1.5 trillion ($A2.08 trillion) for the Pentagon," Senator Tim Kaine said. 

"Everything about that is ridiculous."

Congresswoman Pramila Jayapal described the war as "senseless".

"Billions of taxpayer dollars wasted. Thousands of lives lost. Soaring energy prices," she said.

"That's what Republicans just voted for."

While the president is the commander-in-chief of the US military, only Congress has the authority to declare war.

They also have the power to fund the war, which has cost the Pentagon an estimated A$40 billion so far.

Because Congress did not authorise the war, the costs of it are being pulled from the general Pentagon budget.

The Wall Street Journal reported today that the Pentagon will have to cancel training exercises and other spending because so much money is being diverted to the war with Iran.

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