Some of the country's top bosses are demanding a radical shake-up of the UK's tax rules to prevent businesses from being hauled up on charges of avoidance.
In a submission to the Treasury ahead of next week's Autumn Statement, the Institute of Directors is calling on the government to create a "white list" for authentic tax-planning.
"Firms do not want to fall foul of the law, but currently do not have enough guidance on where the Government draws line between acceptable accounting and aggressive avoidance," the IoD said.
Among other measures, the business group is also calling for a radical consultation to seek a replacement to the current system of corporation tax, which, it said "is becoming increasingly poorly-suited to taxing global businesses."
The IoD offered the measures as a package of reforms to shore up rapidly dropping confidence among bosses over the prospects of the UK economy.
Hammond is due to deliver the Autumn Statement on November 23.
TheCityUK has also drafted its own wishlist ahead of Hammond's first fiscal event next week.
The lobby group's agenda focuses on a “stability first” approach to reassure firms, with objectives including regional investment and cautious tax reform.
However, it is also seeking to press for reassurances around continued access to global talent in the context of the UK's Brexit negotiations, and a promise of a stable Brexit.
Chief executive Miles Celic said: "While the long-term impact of Brexit will depend on the nature of the final deal, any uncertainty and volatility would make for a challenging business environment.
"This Autumn Statement should aim to bring greater market stability and deliver clarity where possible. It is also a prime opportunity to reinforce the fact that Britain remains open for business, and that we can make the most of the opportunities which lie ahead."