The United States’ “One Big Beautiful Bill Act” was signed into law on 4 July 2025, extending a series of lapsed Tax Cuts and Jobs Act provisions and introducing new incentives aimed at research-intensive businesses and investors. Central to the legislation is the reinstatement of immediate expensing for domestic research and development costs under new Section 174A, reversing the five-year amortisation rule that took effect in 2022. Eligible small businesses with average annual gross receipts under $31 million may retroactively deduct R&D outlays back to the 2022 tax year. The measure also broadens the Qualified Small Business Stock regime. For shares issued after enactment, the qualifying asset threshold rises to $75 million, the lifetime gain-exclusion cap increases to $15 million or ten times a holder’s basis, and partial exclusions of 50 percent after three years and 75 percent after four years are introduced. Additional provisions restore the business-interest deduction cap to 30 percent of EBITDA, make the 20 percent Section 199A pass-through deduction permanent, and adjust rules governing real-estate investment trusts, Opportunity Zones, estate taxes and selected clean-energy incentives. Lawmakers backing the package say the changes will lower capital-raising costs for start-ups, simplify planning for small businesses and enhance U.S. competitiveness.