According to Professor Patrick Minford, president of EFT, the dividend is only available if Britain obtains a commercial agreement in the style of Super Canada proposed by Brexiteers or not.
But the bonus will not come with Theresa May's preferred Checkers proposal that links the UK to EU rules.
The additional amount will allow Hammond to make a 4% cut in VAT in 2020, reducing it to 16p in the pound and then in half to 10p in 2025.
The current 20p rate was set by former Chancellor George Osborne in 2010 to help pay for the shortfall left by Gordon Brown's Labor government after the banking crisis.
But due to EU rules, VAT can not be reduced again and much of the revenue collected goes to Brussels.
Brexit activists have pointed out that once Britain is free from the Brussels government in April 2019, Mr. Hammond will be able to reduce VAT and reduce the cost of living.
Peter Bone, the founder of Tory, the founder of Grassroots Out, said: "Exiting a Super Canada agreement or not will mean that Britain is much better after Brexit.
"One of the things we can not do while trapped in the European superstate is to reduce VAT, which affects everyone, especially the most disadvantaged.
"But once we are free from Brussels, we can reduce the VAT again and reduce the cost of living, so I am completely in favor of this Brexit dividend for hard-working Britons."
Professor Minford, who advised Margaret Thatcher, also urged the Chancellor to take advantage of Brexit's economic benefits to cut taxes and spend more on public services, according to an important new report released today by SUN.
He has requested a Post-Brexit Fiscal Fund to demonstrate that "Great Britain was open for business".
The report presents a very different image to that presented by the Chancellor and Treasury officials that taxes will have to increase.
In a scathing analysis, he attacked the Treasury for "not having learned anything from its failed and widely ridiculed forecasts of Project Fear, continues to embark on grim warnings of the effects of Brexit on the economy and, therefore, tax revenues … he consistently fails to present his assumptions to public scrutiny or engage with economists outside of Whitehall. "
"The penumbra of the Treasure fulfills two purposes: to attenuate the demand of expenses of the departments and to push to the government towards the" softer one "of the Brexits, the closest possible to the status quo".
Professor Minford added: "The inescapable conclusion is that the Treasury expects to avoid any scrutiny of its methods (cynically, internally referred to as & # 39; drafting evidence based on policies & # 39;) so that they can make parliamentarians and the public See your negative opinion at that time, from a parliamentary vote on the Brexit. "
As an alternative to reduce VAT, the lead economist has suggested that there could be tax cuts in all areas.
A 1% cut in the bands of income tax, VAT and corporation tax would cost slightly more than 15,000 million pounds, but would stimulate the economy.
The report also finds that the Checkers proposals promoted by Ms. May, in contrast, threaten the economic interests of the United Kingdom.
He says: "Our free trade strategy will be less beneficial, since we can eliminate less protection and also get less return access from other countries that do not belong to the EU. We will not be able to optimize regulations in the main parts of our economy that will be subject to continuous compliance with EU regulations. All company products will be subject to EU regulations, not just those that export to the EU. Also, we will not gain control of our borders. "