Chancellor Kwasi Kwarteng is expected to give a "fiscal statement" on Friday 23 September.
The mini budget will likely deliver some of the tax cuts promised during Liz Truss's Conservative leadership campaign.
The Prime Minister pledged to scrap the rise in National Insurance, cancel the planned rise in corporation tax from 19% to 23%, and raise the point at which individuals start paying income tax.
Truss recently unveiled the Government's plan to support households with rapidly rising energy bills, and Kwarteng may outline equivalent support for businesses, although reports rumour this could be delayed until November.
The energy package will cap the average household's energy bills at £2,500 for two years and suspend green levies, with "equivalent" support to be given to businesses for six months.
On the plan for businesses, Martin McTague, national chair of the Federation of Small Businesses, said:
"This must not result in a cliff-edge after six months, with the withdrawal of support to all but ‘vulnerable' targeted industries, sectors or types of business.
"The definition of who falls in and out of that support will need to be looked at carefully at the three-month review."
There is speculation that Kwarteng could also reduce VAT from 20% to 15%, get rid of VAT on energy bills altogether and extend the 50% business rates relief for hospitality and leisure businesses.
In his first meeting with bank bosses last week, Kwasi Kwarteng said,
"The Prime Minister and I are committed to taking decisive action to help the British people now, while pursuing an unashamedly pro-growth agenda."
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