Osborne has already cut corporation tax from 28% to 25% and it will fall to 23% during this parliament.
But Osborne is determined to give priority to business in his 21 March speech and will set a target of 20% for later years, according to Treasury sources speaking to the Sunday Times.
Elsewhere, the paper suggests Osborne will not tamper with pensions tax relief for higher-rate taxpayers following warnings from the industry.
The Liberal Democrats are among those who want taxpayers earning £60,000 to be stripped of higher rate relief.